Licensed vs. unlicensed spectrum: Key differences

Copyright TechTarget - All rights reserved https://cyber.law.harvard.edu/rss/rss.html Techtarget Feed Generator en Fri, 05 Jun 2026 18:12:22 GMT https://www.techtarget.com/searchnetworking editor@techtarget.com <p>We are surrounded by wireless technologies now more than ever.</p> <p>Some wireless technologies come to mind more easily because we tend to access them for personal use, like Wi-Fi and cellular networks such as <a href="https://www.techtarget.com/searchnetworking/definition/5G">5G</a>. But the wireless concept encompasses an incredibly far-ranging landscape -- from Bluetooth and broadcast technologies to military radars and satellite communications -- each landing in its own slice, or slices, of wireless spectrum.</p> <p>Although the terms <i>spectrum</i> and <i>bands</i> are often used interchangeably, a <i>band</i> starts and stops at discrete frequencies, whereas <i>spectrum</i> is a more generic term for the entire range of radio frequency signals. To keep it straight, a simple example is in order: Wi-Fi <i>spectrum </i>is made up of several discrete <i>bands. </i></p> <p>In the United States, the Federal Communications Commission (FCC) sets rules that govern the use of radio spectrum, and similar agencies exist in other countries around the world. The general regulatory construct for spectrum is that it is either licensed or unlicensed.</p> <p>Unlicensed spectrum allows end users to set up any device they choose, without needing to ask permission as long as they operate within the regulatory limits set for that spectrum. For licensed spectrum, end users must apply to operate specific devices on tightly specified discrete frequencies.</p> <p>It's helpful to understand the differences between licensed vs. unlicensed frequency ranges and how the frequency management landscape is evolving.</p> <section class="section main-article-chapter" data-menu-title="Benefits of licensed spectrum"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Benefits of licensed spectrum</h2> <p>Licensed spectrum ensures consistent performance and reduces the risk of interference because individual companies or users pay a licensing fee for exclusive transmitting rights on discrete frequencies in the spectrum. Licenses are limited and carefully coordinated based on location so a given band remains well-managed from the spectrum perspective, giving a signal its best chance to succeed.</p> <p>To understand licensed bands further, let's go back to simpler times.</p> <p>When broadcast radio and TV were new, specific controlled spectrum was allotted for stations to use. Within that spectrum, individual stations applied for licenses. The frequency channels were specified in each license agreement, along with power output and geographic coverage areas.</p> <p>The license framework was, and still is, designed to make sure an FM radio station on 88.3 MHz, for example, has plenty of space between itself and other stations on the same frequency.  This construct ensures a well-coordinated radio frequency landscape across the licensed frequency ranges. Use cases for licensed spectrum include <a href="https://www.techtarget.com/searchnetworking/definition/5G-infrastructure">cellular networks</a> and high-speed wireless bridges used for network backhaul.</p> <p>Major advantages for technologies that use licensed spectrum include the following:</p> <ul type="disc" class="default-list"> <li><b>Reliability.</b> Because there is no spectrum contention in a location, issues like interference are generally nonexistent provided everyone follows the rules.</li> <li><b>Performance.</b> Each frequency is typically dedicated to a specific use, and systems can generally perform at their best if they're well maintained.</li> <li><b>Protection.</b> If another entity tries to use radio equipment in the same band without authorization, legal remedies in the form of FCC enforcement and other actions are available.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Disadvantages of licensed spectrum"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Disadvantages of licensed spectrum </h2> <p>There is no free lunch when it comes to technology, and every paradigm is a series of tradeoffs. In the case of licensed frequencies, the benefits are balanced by the following disadvantages:</p> <ul type="disc" class="default-list"> <li><b>Fees.</b> Any licensed service has high costs of licensure compared to unlicensed frequencies.</li> <li><b>Bureaucracy.</b> License applications can be complicated, with lengthy approval processes and the need to use third parties to help with paperwork.</li> <li><b>Coveted frequencies aren't always "safe."</b> On occasion, licensed frequencies come under threat from other technologies that petition the FCC for the right to use specific bands, to the possible detriment of incumbent licensees.</li> </ul> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/different_types_of_frequency_bands-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/different_types_of_frequency_bands-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/different_types_of_frequency_bands-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/different_types_of_frequency_bands-f.png 1280w" alt="licensed, unlicensed and lightly licensed frequency bands" height="330" width="559"> <figcaption> <i class="icon pictures" data-icon="z"></i>Check out the differences among licensed, unlicensed and lightly licensed frequency bands. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="Benefits of unlicensed spectrum"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Benefits of unlicensed spectrum </h2> <p>Unlicensed spectrum has a wide range of benefits, including the following:</p> <ul type="disc" class="default-list"> <li><b>Low-cost access.</b> Aside from the purchase price of equipment, frequencies are free for anyone to use, provided users follow regulatory constraints on output power.</li> <li><b>Fast product development.</b> These bands give innovators and other entrepreneurs the opportunity to introduce <a href="https://www.techtarget.com/searchnetworking/feature/5G-in-edge-computing-Benefits-applications-and-challenges">new services and technologies</a> quicker than if they had to apply for permission to use licensed spectrum, which has become increasingly scarce.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Disadvantages of unlicensed spectrum"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Disadvantages of unlicensed spectrum </h2> <p>Despite being easy to use, unlicensed spectrum has its own challenges, including the following:</p> <ul type="disc" class="default-list"> <li><b>Contention.</b> Reliability can be hard to guarantee when several technologies need to coexist in the small swath of spectrum. Interference is common.</li> <li><b>Lack of recourse.</b> To make use of the unlicensed spectrum, device makers and end users must accept that everyone has equal rights to the spectrum. If my wireless camera knocks out your VoIP call on Wi-Fi, not much can be done except to try to reach an agreement on how not to disrupt each other.</li> <li><b>Somewhat wild device market.</b> There is no clean delineation between the enterprise wireless client category and consumer-friendly wireless devices. Consumer devices aren't always carefully regulated for conformance to the FCC's rules or built for use beyond home networks. When consumer devices are brought to work, they can cause havoc for enterprise wireless systems in the same frequency bands.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Lightly licensed spectrum on the rise"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Lightly licensed spectrum on the rise </h2> <p>Even as the FCC attempts to creatively reallocate which technologies are allowed in which band, regulators and industry alike are realizing there are only so many frequencies to use. The endless thirst for more spectrum is driving more use of so-called lightly licensed spectrum bands, such as 3.5 GHz, which is used by <a href="https://www.techtarget.com/searchnetworking/definition/CBRS-Citizens-Broadband-Radio-Service">Citizens Broadband Radio Service (CBRS)</a> systems.</p> <p>These spectrum ranges rely on internet-based databases to control what discrete channel a given component can use based on other channels in that band that might be in use by other CBRS systems or higher-priority users, such as military radar and satellite communications. This model is becoming a popular, FCC-prescribed way to ensure coexistence with other users of the same spectrum, while slightly opening specific bands for new users. Implementing these frequency-control mechanisms can be slow and technically challenging.</p> </section> <section class="section main-article-chapter" data-menu-title="Comparing licensed vs. unlicensed spectrum vs. lightly licensed spectrum"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Comparing licensed vs. unlicensed spectrum vs. lightly licensed spectrum </h2> <p>To recap, each category of spectrum has its own advantages and concerns. Licensed spectrum can be the cleanest and most reliable, but you don't get there without government approval, long lead times and potentially high costs. The device market for licensed spectrum is also fairly small and specialized.<br><br>Unlicensed spectrum makes for easy adoption of devices and quick building of relatively low-cost networks using technologies like Wi-Fi and Bluetooth. But in that spectrum, your devices get no higher priority than mine, and when we're in close physical proximity, we need to find our own path to coexistence. In the U.S., common unlicensed spectrum can be found at 900 MHz, 2.4 GHz, 5 GHz and 6 GHz.</p> <p>Finally, lightly licensed spectrum in the 3.6 GHz band used by CBRS delivers some of the advantages of both licensed and unlicensed spectrum. It costs far less to use and shares spectrum with higher-priority devices by using automated channel selection mechanisms to prevent interference.</p> <p><i>Lee Badman is a network architect specializing in wireless and cloud technologies for a large private university. He's also an author and frequent presenter at industry events.</i></p> </section> Licensed spectrum is reliable and has better performance than unlicensed, which is low cost, easy to deploy and subject to interference. Lightly licensed spectrum offers a balance. https://cdn.ttgtmedia.com/rms/onlineimages/ai_a264431831.jpg https://www.techtarget.com/searchnetworking/answer/Whats-the-difference-between-licensed-and-unlicensed-wireless Mon, 29 Dec 2025 16:23:00 GMT Licensed vs. unlicensed spectrum: Key differences <p>Selecting cables is a crucial part of network design. The required data rate, cost and distance all dictate the range of choices for each connection. Some connections require an obvious cable option, while others can use one of several compatible cables.</p> <p>The <a href="https://www.techtarget.com/searchnetworking/tip/5-steps-to-achieve-network-infrastructure-modernization">network infrastructure</a> delivers network services, such as file sharing, internet access, printing and email, to end users. That infrastructure usually includes switches, routers and -- underpinning it all -- network cabling, one of the oldest and most essential components of network architecture.</p> <p>The main types of network cables include coaxial, twisted pair -- which includes both shielded and unshielded twisted pair -- and fiber optic. Each type has its own specific uses, so it's essential for network professionals to understand the differences between them to determine which best suits their organization's <a href="https://www.techtarget.com/searchnetworking/tip/Network-design-principles-for-effective-architectures">overall network design</a>.</p> <section class="section main-article-chapter" data-menu-title="A quick history of network cables"> <h2 class="section-title"><i class="icon" data-icon="1"></i>A quick history of network cables</h2> <p>Digital communication is not exactly a new idea. In 1844, Samuel Morse sent a message 37 miles -- from Washington, D.C., to Baltimore -- using his invention, the telegraph. This might seem like a far cry from current computer networks, but the principles remain the same.</p> <p>Morse code is a type of binary system that uses dots and dashes in different sequences to represent letters and numbers. <a href="https://searchdatacenter.techtarget.com/quiz/Test-yourself-on-modern-data-center-networking-architecture">Modern data networks</a> use ones and zeros to achieve the same result.</p> <p>The big difference between now and then is the speed at which data is transmitted. Telegraph operators of the mid-19th century could transmit perhaps four or five dots and dashes per second. Computers can now communicate at speeds of up to 100 Gbps -- or 100,000,000,000 separate ones and zeros every second.</p> <p>Although the telegraph and teletypewriter were the forerunners of data communications, computers advanced with ever-increasing speeds. That advancement drove the development of faster networking equipment. In the process, higher-specification cables and connecting hardware were required.</p> </section> <section class="section main-article-chapter" data-menu-title="1. Coaxial cable"> <h2 class="section-title"><i class="icon" data-icon="1"></i>1. Coaxial cable</h2> <p><a href="https://www.techtarget.com/searchnetworking/definition/coaxial-cable-illustrated">Coaxial cable</a>, or coax, is one option for network cabling. An inner conductive core is surrounded by a conductive, shielding layer. This shielding layer is then surrounded by an outer protective layer.</p> <p>The core that carries the signals is solid copper, copper-shielded steel cable or braided copper. Core and conductive shields operate in differential mode to prevent both the emission of electromagnetic interference and the intrusion of external interference.</p> <p>Coax has a long history. In the mid-19th century, it was used for undersea cabling. Today, it is used in a wide range of applications, including residential broadband, telephone lines, and connections to radio and TV broadcasters.</p> <p>Within data centers, coax is often used for fiber channel connections between servers and disk drives. Its resistance to electrical noise makes it valuable in environments with high levels of noise, such as industrial facilities.</p> <h3>Development of Ethernet</h3> <p>The first Ethernet standard used coax cabling. <a href="https://www.techtarget.com/searchnetworking/feature/Understanding-the-evolution-of-Ethernet">Ethernet was developed in the mid-1970s</a> by Robert Metcalfe and David Boggs at Xerox's Palo Alto Research Center in California. In 1979, Digital Equipment Corp. and Intel joined forces with Xerox to standardize the Ethernet system. The first specification by the three companies, called <i>Ethernet Blue Book</i>, was released in 1980. It was also known as the DIX standard, after the companies' initials.</p> <p>That standard called for speeds of up to 10 Mbps -- 10 Mbps equals 10 million bits per second. The Ethernet standard relied on a large coax backbone cable running throughout the building, with smaller coax cables tapped off at 2.5 meter (m) intervals to connect to the workstations. The larger coax, which was usually yellow, became known as Thick Ethernet, or 10Base-5.</p> <p>Below is a breakdown of the 10Base-5 term:</p> <ul class="default-list"> <li><b>10.</b> The speed -- 10 Mbps.</li> <li><b>Base.</b> The baseband system. Baseband uses all its bandwidth for each transmission. In contrast, broadband splits the bandwidth into separate channels to use concurrently.</li> <li><b>5.</b> The system's maximum cable length -- in this case, 500 m.</li> </ul> <p>In 1983, the <a href="https://whatis.techtarget.com/definition/IEEE-Institute-of-Electrical-and-Electronics-Engineers">IEEE</a> released the official Ethernet standard. It was called IEEE 802.3, after the name of the working group responsible for its development.</p> <p>Version 2, IEEE 802.3a, was released in 1985. This second version is commonly known as Thin Ethernet, or 10Base-2. In this version, the maximum length is 185 m, even though the 2 suggests it should be 200 m. Since 1985, various Ethernet standards have been introduced.</p> <h3>Coaxial cable alternatives</h3> <p>Coax is one of the most common network cables, but several alternatives that provide similar functionality are available. Examples of similar, non-coax cables include the following:</p> <ul class="default-list"> <li><b>Twinax cable. </b>Carries high data rate Ethernet at a lower cost than fiber. The twinax core consists of two wires instead of a single core.</li> <li><b>Passive twinax.</b> Supports short-distance connections. Active twinax includes components that boost signal strength, which enables longer-distance connections.</li> <li><b>Triax and quadrax cables.</b> Used for TV connections but can also carry <a href="https://www.techtarget.com/searchnetworking/definition/Gigabit-Ethernet">Gigabit Ethernet</a>. The triax core is similar to coax, but it has an additional insulation layer and shielding layer. A quadrax core has four individual wires. Both triax and quadrax have extra insulation and shielding layers, which enables the transmission of additional signals or carrying power.</li> </ul> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/types_of_enterprise_network_cables-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/types_of_enterprise_network_cables-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/types_of_enterprise_network_cables-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/types_of_enterprise_network_cables-f.png 1280w" alt="network cable diagram" height="604" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>A diagram of the different types of network cables. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="2. Twisted pair"> <h2 class="section-title"><i class="icon" data-icon="1"></i>2. Twisted pair</h2> <p>Originally invented by Alexander Graham Bell to carry telephone signals, twisted-pair cabling is the most common choice for network cabling.</p> <p>Twisted pair uses copper wires that are, as the name suggests, twisted together in pairs. The twist effect of each pair in the cables ensures that any interference presented or picked up on one cable is canceled by the cable's partner that twists around the initial cable. Twisting the two wires also reduces the electromagnetic radiation emitted by the circuit.</p> <p>Twisted pair cabling comes in two types:</p> <ol class="default-list"> <li>Shielded twisted pair (<a href="https://www.techtarget.com/searchnetworking/definition/shielded-twisted-pair">STP</a>).</li> <li>Unshielded twisted pair (<a href="https://www.techtarget.com/searchnetworking/definition/Unshielded-Twisted-Pair">UTP</a>).</li> </ol> <h3>Shielded twisted pair</h3> <p>In STP, copper wires are first covered by plastic insulation. A metal shield, which consists of metal foil or braid, surrounds the bundle of insulated pairs. Where electromagnetic interference is a serious issue, each pair of wires might be individually shielded in addition to the outer shield. This is known as <i>foil twisted pair </i>(FTP).</p> <p>10 Mbps and 100 Mbps use two pairs of cable to transmit Ethernet. Gigabit throughput requires the use of all four pairs.</p> <h3>Unshielded twisted pair</h3> <p>UTP cable is the most popular type of network cable. It is easy to work with, install, expand and troubleshoot. UTP cables typically contain four pairs of copper wires, with each pair containing two wires twisted together. These pairs are covered by plastic insulation. They do not have any shielding and just have an outer jacket.</p> <p>Most categories of twisted-pair cables are available as UTP. However, some newer categories are also available in combinations of shielded, foil shielded and unshielded.</p> </section> <section class="section main-article-chapter" data-menu-title="Categories of twisted-pair cables"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Categories of twisted-pair cables</h2> <p>The American National Standards Institute and the International Electrotechnical Commission, part of the International Organization for Standardization, established a series of standards, or categories, for twisted pair. Category 1, or Cat1, and Cat2 were not officially standardized, but de facto standards developed over time. Eight categories of cables are currently available.</p> <p>These categories specify the type of copper wire and jacks. The number -- 1, 3, 5 and so on -- refers to the revision of the specification and to the number of twists inside the wire -- i.e., the quality of connection in a jack.</p> <h3>Cat1</h3> <p>Cat1 is typically used for telephone wire and voice communications. This type of wire is not capable of supporting computer network traffic and is not twisted.</p> <p>Telecom companies can use Cat1 to provide Integrated Services Digital Network and public switched telephone network services. In such cases, the wiring between the customer's site and the telecom operator's network is performed using Cat1-type cable. Cat1 is also now used for some <a href="https://internetofthingsagenda.techtarget.com/feature/Everything-you-need-to-know-about-IoT-connectivity-options">low data rate IoT networks</a>.</p> <h3>Cat2</h3> <p>Cat2 cables are network wire specifications, using four pairs of twisted copper wires. These types of wires can support computer network and telephone traffic. Cat2 is used mostly for <a href="https://www.techtarget.com/searchnetworking/definition/Token-Ring">token ring</a> networks and supports speeds up to 4 Mbps. For higher network speeds -- 100 Mbps or higher -- Cat5e or higher must be used.</p> <h3>Cat3</h3> <p>Cat3 cables are four pairs of twisted copper wires. Cat3 was used to support the initial 10 Mbps Ethernet, typically for token ring networks. Although 10 Mbps speeds are almost extinct, some deployments still use Cat3.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/utp_categories-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/utp_categories-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/utp_categories-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/utp_categories-f.png 1280w" alt="Categories of twisted pair cables" height="336" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>Use this chart to compare the different categories of twisted pair cables. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <h3>Cat4</h3> <p>Cat4 cables are four pairs of twisted copper wires. As with Cat3 cables, Cat4 is used for token ring networks. While Cat3 provides support of a maximum of 10 Mbps, Cat4 pushed the limit up to 16 Mbps. Both categories have a length limit of 100 m. Cat4 is not widely used.</p> <h3>Cat5 and Cat5e</h3> <p>Cat5 cables are four pairs of twisted copper wires. Cat5 has more twists per inch than Cat3, so it can run at higher speeds and greater lengths.</p> <p>The more popular Cat5 wire has largely been replaced by the Cat5e specification. Cat5e provides improved crosstalk specification, enabling it to support speeds of up to 1 Gbps.</p> <p>UTP-Cat5e is one of the more popular UTP cables. It replaced old coax cables that were unable to keep up with the constantly growing need for faster and more reliable networks. Cat5e is the most widely used type of network cabling specification worldwide and is a cost-effective option. Unlike the category cables that follow, it is forgiving when cable termination and deployment guidelines are not met.</p> <p>Cat5 and Cat5e are more widely used for both 10 Mbps and 100 Mbps Ethernet.</p> <h3>Cat6 and Cat6a</h3> <p>Cat6 wire was originally designed to support Gigabit Ethernet, although other standards enable Gigabit transmission over Cat5e wire. Cat6 is similar to Cat5e wire, but it contains a physical separator between the four pairs to further reduce electromagnetic interference.</p> <blockquote class="main-article-pullquote"> <div class="main-article-pullquote-inner"> <figure> No one type of cable is appropriate everywhere. </figure> <i class="icon" data-icon="z"></i> </div> </blockquote> <p>Cat6 can support speeds of 1 Gbps for lengths of up to 100 m. It also supports 10 Gbps for lengths of up to 55 m. It uses bandwidth frequencies up to 250 MHz.</p> <p>When installing new Cat6 cables, all cabling components -- jacks, patch panels, patch cords and the like -- must be Cat6-certified. This requires network pros to be extra cautious about the proper termination of the cable ends. Organizations performing installations using Cat6 cabling should request a thorough test report, using a certified cable analyzer, to ensure the installation has been performed according to Cat6 guidelines and standards.</p> <p>In 2009, Cat6a was introduced as a higher specification cable, offering better immunity from crosstalk and electromagnetic interference. It offers better bandwidth using frequencies up to 500 MHz, supports 10 Gbps and has a cable length up to 100 m.</p> <h3>Cat7</h3> <p>Cat7 is a copper cable specification designed to support speeds of 10 Gbps at lengths of up to 100 m. To achieve this, the cable uses FTP for four individually shielded pairs, plus an additional cable shield to protect the signals from crosstalk and electromagnetic interference.</p> <p>Due to extremely high data rates, all components used throughout the installation of a Cat7 network cabling infrastructure must be Cat7-certified. This includes patch panels, patch cords, jacks and RJ-45 connectors. The absence of Cat7-certified components will degrade overall performance and lead to the failure of any Cat7 certification tests -- for example, using a cable analyzer -- because Cat7 performance standards are most likely not met.</p> <p>Cat7 is usually used in data centers for backbone connections among servers, network switches and storage devices.</p> <h3>Cat8</h3> <p>Cat8 is a newer category of twisted-pair cabling that competes more effectively with the speed and scale of <a href="https://www.techtarget.com/searchnetworking/definition/fiber-optics-optical-fiber">fiber optics</a>. It has a maximum data rate of 40 Gbps and uses RJ-45 connectors. It uses the 2 GHz -- or 2,000 MHz -- frequency, an increase from Cat7's 600 MHz.</p> <p>Cat8 cables are typically used in data center environments. They are backward-compatible with previous standards and support Power over Ethernet (<a href="https://www.techtarget.com/searchnetworking/definition/Power-over-Ethernet">PoE</a>).</p> <p>PoE eliminates the need to run a separate power wire to devices, such as ceiling-installed access points. For low data rates, PoE cables supply power using the pairs not needed for Ethernet. For higher rates, where all four pairs are used, PoE adds direct current to the wires carrying the signal, without interfering with the signals.</p> </section> <section class="section main-article-chapter" data-menu-title="3. Fiber optic cable"> <h2 class="section-title"><i class="icon" data-icon="1"></i>3. Fiber optic cable</h2> <p>Data rates have increased throughout the network, and in some cases, fiber optics is the only option. While Cat8 twisted-pair cables can carry up to 40 Gbps of data, fiber supports data rates up to 400 Gbps. Work is currently underway to <a href="https://spectrum.ieee.org/infinera-and-windstream-beam-800-gigabits-per-second-through-a-single-optical-fiber">test 800 Gbps</a>.</p> <p>Fiber optic cables consist of a thin optical fiber surrounded by cladding. Cladding is made from glass that is less pure than the core and has a lower refractive index than the core. The difference in refractive indices causes light to be reflected at the boundary. Additional layers, such as the buffer layer and jacket layer, surround the cladding to add strength and protect the cable against damage.</p> <p>Fiber has a low error rate. Network data is encoded in a light beam. Unlike twisted-pair cables, the light beam neither generates nor is affected by electronic interference. Additionally, multiple frequency data streams can be multiplexed over a single fiber to increase the total data rate.</p> <h3>Multimode fiber vs. single-mode fiber</h3> <p>Fiber types differ by the diameter of the fiber. Multimode optical fiber ranges from 50 microns to 100 microns (10<sup>-4</sup> m). In a single-mode cable, the optical fiber is only 8 microns to 10.5 microns in diameter.</p> <p>Multimode cable is less expensive to make and install than single mode, but it is limited in data rate and distance. While multimode can carry 100 Gbps for 150 m, single mode can carry 400 Gbps for up to 10 kilometers and lower rates for additional distances.</p> <p>Performance varies between multimode and single-mode fiber due to the way light travels through each. The larger fiber used in multimode causes the light beam to reflect from the fiber and cladding boundary at a steeper angle than the thinner core in single mode. Single mode's thinner core causes the distance between reflections to be smaller. When reflections are more frequent, losses are larger at the boundary.</p> </section> <section class="section main-article-chapter" data-menu-title="No choice is permanent"> <h2 class="section-title"><i class="icon" data-icon="1"></i>No choice is permanent</h2> <p>No one type of cable is appropriate everywhere. Supported data rates, installed cost and future adequacy must be considered for each application. Ongoing maintenance costs should also be a factor.</p> <p>Remember, no choice is permanent. Just as organizations periodically replace servers and workstations, they can reconsider their choice of <a href="https://www.techtarget.com/searchnetworking/answer/What-does-a-network-infrastructure-upgrade-project-involve">connection technology for each network upgrade</a>.</p> <p><i>Chris Partsenidis is founder and editor in chief of Firewall.cx, a globally recognized network security website. He holds multiple certifications, including Cisco CCNP, and was named a 2015 Cisco Champion for Enterprise Networking.</i></p> <p><i>David Jacobs has more than 30 years of networking industry experience. He has managed leading-edge hardware and software development projects as well as consulted Fortune 500 companies and software startups.</i></p> </section> The main types of network cables are coax, fiber optics, and shielded and unshielded twisted pair. As enterprises deploy new technologies, it's critical to select the right cables. https://cdn.ttgtmedia.com/visuals/searchDataCenter/infrastructure/datacenter_article_023.jpg https://www.techtarget.com/searchnetworking/tutorial/Network-cable-history-and-fundamentals-Cabling-tips-for-network-professionals-lesson-1 Mon, 29 Dec 2025 09:45:00 GMT What are the different types of network cables? <p>In wireless security, passwords are only half the battle. Choosing the proper level of encryption is just as vital, and the right choice determines whether your wireless LAN is a house of straw or a resilient fortress.</p> <p>Wireless security protocols have evolved over time to address issues, enhance compatibility and strengthen security compared to their predecessors. Wired Equivalency Protocol (WEP) is the original wireless standard developed by the <a href="https://www.techtarget.com/searchnetworking/reference/IEEE-802-Wireless-Standards-Fast-Reference">IEEE</a> in 1997 to provide a security standard for wireless networks. Being new for its time, WEP had several security vulnerabilities that were later addressed in 2004, when Wi-Fi Alliance released Wi-Fi Protected Access (WPA) as its successor. WPA built upon WEP by addressing its security flaws.</p> <p>WPA was more of a temporary standard used to address the latter's issues, as it soon became obsolete in 2004 in favor of WPA2, a faster and more secure protocol. WPA2 was a long-term standard that remained the most dominant security protocol until 2018, when Wi-Fi Alliance introduced <a href="https://www.techtarget.com/searchsecurity/definition/WPA3">WPA3</a>. Although WPA3 is the latest wireless security standard, most organizations continue to use WPA2.</p> <section class="section main-article-chapter" data-menu-title="Why wireless encryption matters for enterprises"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Why wireless encryption matters for enterprises</h2> <p><a name="_Hlk216112300"></a>Encryption is the process of converting data into ciphertext that requires the proper keys for decryption, making it difficult to decode. Encryption happens at many layers. Business applications and web commerce are all encrypted, whether using an encrypted Wi-Fi connection or a VPN, so wireless network encryption is arguably less significant than it once was.</p> <p>Wi-Fi encryption, in addition to the application-specific encryption in use, provides a comprehensive security baseline for all client devices. This prevents unencrypted applications from posing a security risk. <a name="_Hlk216112580"></a>Encryption also helps make the WLAN environment more secure from a topology perspective, as a defense against other potential vulnerabilities.</p> </section> <section class="section main-article-chapter" data-menu-title="How unsecured wireless networks create risks"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How unsecured wireless networks create risks</h2> <p>Wireless networks require security protocols to ensure they remain secure, efficient and are compatible between various devices. Wireless networks without these standards could potentially face multiple security risks, such as the following:</p> <ul class="default-list"> <li><b>Compromised data. </b>An unsecured network is at risk of being compromised by internal or external threat actors seeking to steal data, <a href="https://www.techtarget.com/searchsecurity/answer/How-to-prevent-network-sniffing-and-eavesdropping">eavesdrop</a> or perform other malicious activities. Anyone within range can intercept the radio waves carrying Wi-Fi traffic without the need to access physical hardware directly.</li> <li><b>Expanded attack surface. </b>Threat actors can use unsecured wireless networks as a point of vulnerability to gain access to the broader enterprise network. Encryption doesn't necessarily fix this problem, but attackers who see a WLAN with outdated encryption protocols in place might attempt to exploit other weak spots in the wireless network.</li> <li><b>Malware distribution.</b> Hackers who gain access to the network can distribute viruses, ransomware or other malware across devices connected to it. This can lead to data breaches that create <ins datetime="2025-12-09T16:59" cite="mailto:Darah,%20Deanna"><a href="https://www.techtarget.com/searchnetworking/feature/The-effects-of-network-downtime-and-ways-to-fix-it">network downtime</a></ins> and lead to financial loss for the organization.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="How each wireless security protocol works"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How each wireless security protocol works</h2> <p>Most wireless APs come with the ability to enable one of four wireless encryption standards:</p> <ol class="default-list"> <li>Wired Equivalent Privacy (WEP).</li> <li>Wi-Fi Protected Access (WPA).</li> <li>WPA2.</li> <li>WPA3.</li> </ol> <p>WEP is the first generation of wireless security protocols, followed by WPA. However, organizations should avoid these older WLAN security standards, as they have been deprecated. Not only are WEP and WPA easily crackable by commoditized applications, but they also indicate that the client devices restricted to them are outdated and could <a href="https://www.techtarget.com/searchnetworking/tip/Three-ways-to-measure-wireless-network-performance">jeopardize WLAN performance</a>.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/networking-wireless_security_cheat_sheet-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/networking-wireless_security_cheat_sheet-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/networking-wireless_security_cheat_sheet-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/networking-wireless_security_cheat_sheet-f.png 1280w" alt="Comparison chart of WEP, WPA, WPA2 and WPA3" height="310" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>Compare the different wireless encryption standards to learn how they work and if you should use them. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="How WPA2 works"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How WPA2 works</h2> <p>As the successor to WPA, WPA2 was ratified by the IEEE in 2004 as 802.11i. WPA2's strength comes from using <a href="https://www.techtarget.com/searchsecurity/definition/Advanced-Encryption-Standard">Advanced Encryption Standard</a> and <a href="https://www.techtarget.com/searchsecurity/definition/CCMP-Counter-Mode-with-Cipher-Block-Chaining-Message-Authentication-Code-Protocol">Counter Mode with Cipher Block Chaining Message Authentication Code Protocol</a>, an authentication mechanism.</p> <ul class="default-list"> <li><b>AES. </b>Developed by the U.S. government to protect classified data, AES comprises three symmetric block ciphers. Each cipher encrypts and decrypts data in blocks of 128 bits using 128-, 192- and 256-bit keys, relying on the increased processing power of modern Wi-Fi hardware and client devices.</li> <li><b>CCMP</b>. Protects data confidentiality by allowing only authorized network users to receive data. It uses cipher block chaining message authentication code to ensure message integrity.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="KRACK vulnerability exposes WPA2 flaws"> <h2 class="section-title"><i class="icon" data-icon="1"></i>KRACK vulnerability exposes WPA2 flaws</h2> <p>WPA2 was a significant step forward in Wi-Fi security, but two major flaws eventually emerged:</p> <ol class="default-list"> <li>The key exchange used in WPA2 has inherent weaknesses that make it a poor fit for sensitive data.</li> <li><a href="https://www.techtarget.com/searchsecurity/tip/Why-WPA2-PSK-can-be-a-security-risk-even-with-an-uncracked-key">WPA2-Personal</a>, which uses preshared keys, is only as strong as the PSK password used to secure it.</li> </ol> <h3>KRACK vulnerability</h3> <p>WPA2 has a major drawback known as the <a href="https://www.techtarget.com/searchsecurity/answer/How-does-the-KRACK-vulnerability-use-encryption-keys">key reinstallation attack (KRACK) vulnerability</a>, which exploits the reinstallation of wireless encryption keys. WPA2-Enterprise has a stronger authentication scheme than WPA2-Personal due to its use of Extensible Authentication Protocol. However, the KRACK vulnerability exists at the encryption stage. As a result, it affects all WPA2 implementations.</p> <p>Industry analysts widely acknowledged KRACK as a serious WPA2 security flaw. The finding prompted technology providers to quickly roll out software patches to mitigate risk until the arrival of the next generation of wireless security. But many experts argued the <a href="https://www.techtarget.com/searchsecurity/news/450428414/KRACK-WPA2-vulnerability-might-be-more-hype-than-risk">KRACK vulnerability would prove difficult to exploit</a> in the real world.</p> <h3>Weak PSKs compromise the four-way handshake</h3> <p>A new Wi-Fi network connection begins with a cryptographic four-way handshake between an endpoint and AP.</p> <ol class="default-list"> <li>Both devices prove they know a preestablished authentication code -- Pairwise Master Key (PMK) in enterprise mode and PSK in personal mode -- without either one revealing it explicitly through a series of back-and-forth messages.</li> <li>The client device sends a cryptographic response to the AP to confirm that both devices generated the same encryption key.</li> <li>The AP passes a traffic encryption key to the client.</li> <li>If the endpoint doesn't acknowledge it has received the key, the AP assumes a connectivity issue, resending and reinstalling it repeatedly.</li> </ol> <p>KRACK attackers -- who must be within physical range of both the client and the network -- can trigger, capture, analyze, manipulate and replay those retransmissions until they're able to determine the key, break encryption and gain access to network data.</p> <p>The four-way handshake method also makes WPA2 networks with weak passcodes vulnerable to offline dictionary attacks, a type of brute-force attack that involves systematically trying hundreds, thousands or millions of pre-compiled possible passwords, out of earshot of the target network.</p> <p><a name="_Hlk216183840"></a>An attacker could capture a WPA2 handshake, take that information offline and use a computer program to compare it against a list of likely codes. This process continues until they find a code that aligns logically with the available handshake data. Dictionary attacks are less likely to succeed against long and complex <a href="https://www.techtarget.com/searchsecurity/tip/Top-5-password-hygiene-tips-and-best-practices">passwords with combinations</a> of uppercase and lowercase letters, numbers and special characters.</p> <div class="youtube-iframe-container"> <iframe id="ytplayer-0" src="https://www.youtube.com/embed/l71GBlds0Rs?autoplay=0&modestbranding=1&rel=0&widget_referrer=null&enablejsapi=1&origin=https://www.techtarget.com" type="text/html" height="360" width="640" frameborder="0"></iframe> </div> </section> <section class="section main-article-chapter" data-menu-title="How WPA3 works"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How WPA3 works</h2> <p>In 2018, Wi-Fi Alliance began certification for WPA3, the most recent and most secure wireless security standard. As of July 2020, Wi-Fi Alliance <a href="https://www.wi-fi.org/security">required all devices</a> seeking Wi-Fi certification to support WPA3. New features and requirements include the following:</p> <ul class="default-list"> <li><b>Protected Management Frames. </b>Required in WPA3 and optional in prior standards. PMFs help guard against eavesdropping and forging. It also standardizes the 128-bit cryptographic suite and disallows obsolete security protocols. WPA3-Enterprise has optional 192-bit security encryption and a 48-bit IV for heightened protection of sensitive corporate, financial and governmental data.</li> <li><b>Stronger CCMP. </b>WPA3-Personal uses CCMP-128 and AES-128, whereas the enterprise version with 802.1X offers stronger protection options.</li> <li><b>More secure cryptographic handshake. </b>Replaces the legacy PSK four-way handshake with simultaneous authentication of equals. SAE eliminates the reuse of encryption keys, requiring a new code with every interaction. Without open-ended communication between AP and client or the reuse of encryption keys, cybercriminals can't easily eavesdrop or insert themselves into an exchange.</li> <li><b>Wi-Fi Easy Connect. </b>Introduced by Wi-Fi Alliance alongside WPA3. Wi-Fi Easy Connect simplifies the onboarding process for IoT devices without visual configuration interfaces using a mechanism such as a QR code scan.</li> <li><b>Wi-Fi Enhanced Open.</b> Safeguards connecting to public Wi-Fi networks by automatically encrypting information between each client and AP using a new unique key.</li> <li><b>Opportunistic Wireless Encryption.</b> Provides an automatic key exchange for devices that support it. OWE also offers eavesdropping-resistant encryption with no user intervention.</li> </ul> <p>WPA3 is not impervious to threats, however. WPA3 has design and implementation flaws known as Dragonblood vulnerabilities. These include two downgrade attacks, in which an attacker forces a device to revert to WPA2, and two side-channel attacks, which enable offline dictionary attacks. However, according to Wi-Fi Alliance, vendors could readily mitigate them with software upgrades.</p> </section> <section class="section main-article-chapter" data-menu-title="WPA3: The most secure Wi-Fi protocol"> <h2 class="section-title"><i class="icon" data-icon="1"></i>WPA3: The most secure Wi-Fi protocol</h2> <p>Experts agree WPA3 is best for Wi-Fi security, as it's the most up-to-date wireless encryption protocol. Some wireless APs do not support WPA3, however. In that case, the next best option is WPA2, which is widely deployed in the enterprise space today.</p> <p><a name="_Hlk216188312"></a>Because WEP or WPA are outdated and insecure, network administrators should replace any <a href="https://www.techtarget.com/searchnetworking/answer/Is-there-a-difference-between-a-wireless-access-point-and-a-wireless-router">wireless AP or router</a> that supports WEP or WPA with a newer device compatible with WPA2 or WPA3.</p> </section> <section class="section main-article-chapter" data-menu-title="Best practices for Wi-Fi deployment and migration"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Best practices for Wi-Fi deployment and migration</h2> <p>There is no single best approach to wireless security. Successful implementation begins with defining specific requirements tailored to the situation and client device capabilities. Not all environments require the most comprehensive security, the necessary infrastructure and the costs that come with it.</p> <p>Certain situations, such as those involving PCI or HIPAA, for example, require stronger security than others. Wi-Fi security also needs to be designed for compliance where regulatory guidance is mandated. In other situations, organizations must weigh the decision to use 802.1X-based security or PSK-based encryption. This decision comes down to the ease of use and the complexity of implementation.</p> <p>Organizations can secure even an open wireless network by only allowing clients to access the internet or a targeted in-house destination with secure applications. </p> <p>Defining requirements is often one of the most challenging aspects of wireless security. Implementation difficulty will depend on complexity of the requirements. Organizations might find they need multiple types of security in one environment for different use cases. The choice will require ongoing periodic auditing or penetration testing, as well as monitoring for new vulnerabilities of current protocols that become obsolete.</p> <p><i>Jessica Scarpati is a Boston-based freelance writer. She is the former features and e-zine editor for Informa TechTarget's SearchNetworking Media Group.</i></p> <p><i>Alissa Irei is senior site editor of Informa TechTarget's SearchSecurity.</i></p> <p><i>Lee Badman is a network architect specializing in wireless and cloud technologies for a large private university. He's also an author and frequent presenter at industry events.</i></p> </section> As wireless networks have evolved, so have the protocols for securing them. Get an overview of WLAN security standards, and learn the differences among WEP, WPA, WPA2 and WPA3. https://cdn.ttgtmedia.com/visuals/searchCIO/enterprise_security/cio_article_014.jpg https://www.techtarget.com/searchnetworking/feature/Wireless-encryption-basics-Understanding-WEP-WPA-and-WPA2 Wed, 10 Dec 2025 13:00:00 GMT Wireless security: Differences between WEP, WPA, WPA2, WPA3 <section class="section main-article-chapter" data-menu-title="What is a phase-locked loop (PLL)?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>What is a phase-locked loop (PLL)?</h2> <p>A phase-locked loop (PLL) is an electronic circuit with a voltage or voltage-driven oscillator that constantly adjusts to match the frequency of an input signal. PLLs are used to generate, stabilize, <a href="https://www.techtarget.com/searchnetworking/definition/modulation">modulate</a>, demodulate, filter or recover a signal from a "noisy" communications channel where data has been interrupted.</p> <p>PLLs are widely used in <a href="https://www.techtarget.com/searchmobilecomputing/definition/wireless-router">wireless</a> or radio frequency (<a href="https://www.techtarget.com/searchnetworking/definition/radio-frequency">RF</a>) applications, including Wi-Fi routers, broadcast radios, walkie-talkie radios, televisions and mobile phones.</p> <p>At its simplest, a phase-locked loop is a closed-loop feedback control circuit that's both frequency- and phase-sensitive. A PLL is not a single component, but a system that consists of both analog and digital components -- interconnected in a "<a href="https://www.techtarget.com/searchitchannel/definition/feedback-loop">negative feedback</a>" configuration. Consider it analogous to an elaborate operational amp (op amp)-based <a href="https://www.techtarget.com/whatis/definition/amplifier">amplifier</a> circuit.</p> </section> <section class="section main-article-chapter" data-menu-title="What is a phase-locked loop used for?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>What is a phase-locked loop used for?</h2> <p>The main goal of a PLL is to synchronize the output <a href="https://www.techtarget.com/whatis/definition/oscillator">oscillator</a> Signal with a reference signal. Even if the two signals have the same frequency, their peaks and troughs may not occur in the same place. Simply put, they do not reach the same point on the waveform at the same time.</p> <p>Known as the <a href="https://www.techtarget.com/whatis/definition/phase">phase</a> difference<em>, </em>this is measured as the angle between the signals. For signals with varying frequencies, the phase difference between them will always vary, which means that one signal will lag or lead the other by a varying amount.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/networking-phase_difference_illustrated-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/networking-phase_difference_illustrated-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/networking-phase_difference_illustrated-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/networking-phase_difference_illustrated-f.png 1280w" alt="Phase difference illustrated" height="510" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>During a phase difference, the leading phase refers to a wave occurring 'ahead' of a different wave of the same frequency, while the lagging phase indicates waves occurring 'behind' another of the same frequency. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>A PLL reduces phase errors between output and input frequencies. When the phase difference between these signals is zero, the system is said to be "locked." And this locking action depends on the PLL's ability to provide negative feedback -- i.e., route the output signal back to the phase detector.</p> <p>In addition to synchronizing the output and input frequencies, a PLL also helps establish the input-output phase relationship to generate the appropriate control voltage. Therefore, it helps achieve <em>both</em> frequency and phase lock in a circuit.</p> </section> <section class="section main-article-chapter" data-menu-title="Key components of a phase-locked loop"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Key components of a phase-locked loop</h2> <p>A PLL consists of three key components:</p> <ul class="default-list"> <li><strong>Phase detector</strong> (also known as a phase comparator or mixer). It compares the phases of two signals, and generates a voltage according to the phase difference. It multiplies the reference input and the voltage-controlled oscillator output.</li> <li><strong>Voltage-controlled oscillator</strong>. Generates a sinusoidal signal, whose frequency closely matches the center frequency provided by the low-pass filter.</li> <li><strong>Low-pass filter</strong>. A kind of <a href="https://www.sciencedirect.com/topics/engineering/loop-filter" target="_blank" rel="noopener">loop filter</a> that attenuates the high-frequency alternating current (AC) component of the input signal to smoothen and flatten the signal to make it more DC-like.</li> </ul> <p>Here, the phase detector functions as an <em>analog </em><a href="https://resources.pcb.cadence.com/blog/2019-analog-multipliers-and-rf-modulators-introduction-and-applications" target="_blank" rel="noopener"><em>multiplier</em></a>, the voltage-controlled oscillator as a <a href="https://www.analog.com/en/products/amplifiers/rf-amplifiers/gain-blocks.html" target="_blank" rel="noopener"><em>gain</em></a><em> block,</em> and the low-pass filter as a <a href="https://www.mathworks.com/help/physmod/sps/powersys/ref/leadlagfilter.html" target="_blank" rel="noopener"><em>lag</em></a><em> block</em>.</p> <p>Together, the phase-locked loop, voltage-controlled oscillator, <a href="https://www.apitech.com/products/ima-subsystems/oscillator-ima/master-reference-oscillators-mro/" target="_blank" rel="noopener">reference</a> oscillator and <a href="https://www.eeeguide.com/phase-comparator-circuit/" target="_blank" rel="noopener">phase comparator</a> comprise a <em>frequency synthesizer</em> -- an electronic system that produces a range of frequencies from a single fixed oscillator. Wireless equipment that use this type of frequency control are said to be frequency-synthesized.</p> <p>Other frequency-synthesized devices include:</p> <ul class="default-list"> <li>mobile phones</li> <li>satellite receivers</li> <li><a href="https://www.techtarget.com/searchmobilecomputing/definition/Global-Positioning-System">GPS</a> systems</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="How a phase-locked loop works"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How a phase-locked loop works</h2> <p>The underlying mechanism of a PLL operates based on the phase difference between two signals. It detects this difference, and provides a feedback mechanism to modify the voltage-controlled oscillator frequency.</p> <p>The PLL compares the voltage-controlled oscillator signal with the input/reference signal. Because the PLL is both frequency- and phase-sensitive, it can detect both frequency and phase differences between the two signals.</p> <p>It generates an error signal that corresponds to the phase difference between the signals. This difference is passed on to the low-pass filter that removes any high-frequency elements, and filters the error signal into a varying direct current (<a href="https://www.techtarget.com/whatis/definition/DC-direct-current">DC</a>) level. This "feedback signal" is then applied back to the voltage-controlled oscillator to control its frequency.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/networking-phase_locked_loop_at_its_most_basic-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/networking-phase_locked_loop_at_its_most_basic-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/networking-phase_locked_loop_at_its_most_basic-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/networking-phase_locked_loop_at_its_most_basic-f.png 1280w" alt="Diagram of a phase-locked loop" height="215" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>A simplified look at how a phase-locked loop works constantly to adjust voltage to match input signal frequency. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>To start, this loop will be out of lock. The error signal will pull the voltage-controlled oscillator frequency toward the reference frequency, and continue to do so until it cannot reduce the error any further. At one point, however, the phase difference between the two signals will become zero (i.e., they will both be on exactly the same frequency).</p> <p>This is when the loop is said to be locked, and a steady-state error voltage is produced.</p> </section> <section class="section main-article-chapter" data-menu-title="Common phase-locked loop applications"> <h2 class="section-title"><i class="icon" data-icon="1"></i><span>Common phase-locked loop applications</span></h2> <p>PLLs are used in dozens of applications; among them are:</p> <ul class="default-list"> <li>telecommunications systems</li> <li>computers</li> <li>radio</li> <li>other electronic systems</li> </ul> <p>Phase-locked loops are frequently used in <a href="https://www.techtarget.com/searchmobilecomputing/definition/wireless">wireless</a> communication, primarily for Frequency Modulation (<a href="https://www.techtarget.com/searchnetworking/definition/modulation">FM</a>) transmissions, where they enable high-quality audio to be demodulated from an FM signal. They are also employed for Phase Modulation (PM) transmissions.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/networking-apf_modulation-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/networking-apf_modulation-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/networking-apf_modulation-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/networking-apf_modulation-f.png 1280w" alt="Three kinds of wave modulation: phase, frequency and amplitude" height="510" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>The three types of wave modulation, which is the conversion of data into radio waves by adding information to a signal. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>Indirect frequency synthesizers are another important application of PLL. Two other key PLL applications are:</p> <ul class="default-list"> <li><strong>Timing distribution.</strong> To distribute precisely timed clock pulses in digital logic circuits (e.g., in microprocessor systems).</li> <li><strong>Signal recovery.</strong> To provide a "clean" signal and remember the frequency in case of interruptions (e.g., when using pulsed transmissions).</li> </ul> <p><a href="https://www.techtarget.com/whatis/definition/digital">Digital</a> data transmissions uses phase-locked loops more commonly than analog transmissions. They are also more commonly manufactured as integrated circuits, although discrete <a href="https://www.techtarget.com/whatis/definition/circuit">circuits</a> are used for <a href="https://www.techtarget.com/searchnetworking/definition/microwave">microwave</a> signal processing.</p> </section> A phase-locked loop (PLL) is an electronic circuit with a voltage or voltage-driven oscillator that constantly adjusts to match the frequency of an input signal. https://cdn.ttgtmedia.com/visuals/digdeeper/2.jpg https://www.techtarget.com/searchnetworking/definition/phase-locked-loop Fri, 21 Nov 2025 13:19:00 GMT phase-locked loop (PLL) <p>Infrastructure managers have to track thousands of components <a href="https://www.techtarget.com/searchnetworking/tip/An-introduction-to-8-types-of-network-devices">needed to run their networks</a> -- across a single building, multiple sites within a city or multiple buildings in an open campus.</p> <p>Enter cable management software. These systems help admins pinpoint where every connection is, the type of cable and connectors used, and each connection made within the infrastructure.</p> <p>Figure 1 illustrates the various kinds of cabling deployed in a typical building. Cable management software keeps track of the characteristics of each connection and the devices to which each cable segment connects, such as servers, IP private branch exchanges, switches, routers and hubs.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/infrastructure_elements-f.jpg"> <img data-src="https://www.techtarget.com/rms/onlineimages/infrastructure_elements-f_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/infrastructure_elements-f_mobile.jpg 960w,https://www.techtarget.com/rms/onlineimages/infrastructure_elements-f.jpg 1280w" alt="Cable management software capture of infrastructure elements" data-credit="Paul Kirvan" height="625" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i> Figure 1. Infrastructure elements captured by cable management software. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>Cable management software tracks each network infrastructure element noted in Figure 1. Most software products also generate a visual map of the network with details of each element.</p> <p>Cable management systems should be compatible with industry standards for cable and structured network distribution systems. The most widely used reference is the <a target="_blank" href="https://www.tiafotc.org/ansi-tia-568-d/" rel="noopener">ANSI/TIA 568 series of standards</a> that specifies how to implement both residential and commercial building cable distribution systems.</p> <section class="section main-article-chapter" data-menu-title="Pros and cons of cable management software"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Pros and cons of cable management software</h2> <p>Cable management software is essential for today's complex enterprise networks.</p> <h3>Pros of cable management software</h3> <p>Benefits of cable management software include the following:</p> <ul class="default-list"> <li><b>Accurate cable infrastructure details</b>. <a href="https://www.techtarget.com/searchnetworking/tip/Network-cabling-documentation">Verifies</a> every connection, cable route and hardware component<a href="https://www.techtarget.com/searchnetworking/tip/Network-cabling-documentation"></a>. This reduces the need for manual tracking using spreadsheets or other methods.</li> <li><b>Faster problem troubleshooting</b>. Identifies potential issues quickly, speeding up repairs and reducing downtime.</li> <li><b>Efficient infrastructure management</b>. Facilitates planning when changes to the networks are needed, reducing human errors.</li> <li><b>Flexibility and scalability</b>. Adapts to infrastructure changes, such as adding more locations, moving an office or integrating cloud resources.</li> <li><b>Enhanced system integration</b>. Links to specialized platforms such as data center infrastructure management (<a href="https://www.techtarget.com/searchdatacenter/definition/data-center-infrastructure-management-DCIM">DCIM</a>), configuration management database (<a href="https://www.techtarget.com/searchdatacenter/definition/configuration-management-database">CMDB</a>), IT service management and network monitoring systems.</li> <li><b>Visualized infrastructure</b>. Generates 2D and 3D images of the network.</li> </ul> <h3>Cons of cable management software</h3> <p>Drawbacks of cable management software include the following:</p> <ul class="default-list"> <li><b>Expensive</b>. Costs can be significant, depending on the complexity of the network and the functions to be delivered.</li> <li><b>Learning challenges</b>. Training is essential and learning the system may be time-consuming for both primary and alternate users.</li> <li><b>Maintenance requirements</b>. Keeping the system database up to date can be challenging.</li> <li><b>Security and access control</b>. Protecting the system from unauthorized access is a must; a breach could make network data visible to cyberattacks.</li> <li><b>Integration challenges</b>. Connecting the system to work with a variety of platforms might require additional programming if the system <a href="https://www.techtarget.com/searchdatamanagement/feature/5-data-integration-challenges-and-how-to-overcome-them">can't perform the necessary interfaces</a>.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Cable management software selection criteria"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Cable management software selection criteria</h2> <p>Organizations must ask vendor candidates important questions when evaluating prospective products. Examples of questions to ask include the following:</p> <ul class="default-list"> <li>Is the software locally deployed or is it cloud-based?</li> <li>Is it a commercial product or open source?</li> <li>How long does it take to build the database?</li> <li>What support does the vendor provide when building the database?</li> <li>How does the software visually display the network map?</li> <li>Can the software delineate between <a href="https://www.techtarget.com/searchnetworking/tutorial/Network-cable-history-and-fundamentals-Cabling-tips-for-network-professionals-lesson-1">different types of cables</a> and connectors?</li> <li>How much detail can the software capture for items like cable racks, patch panels, ports and cable routing paths?</li> <li>How easy is it to update the database?</li> <li>How are software updates, such as patches and downloads, delivered?</li> <li>How does the software present out-of-normal conditions?</li> <li>Does the software have a dashboard or similar feature to display the infrastructure in real time?</li> <li>How well does the software integrate with platforms such as DCIM and CMDB?</li> <li>How quickly can the software scale and adapt to changing requirements?</li> <li>What licensing issues must be addressed?</li> <li>Can a <a href="https://www.techtarget.com/searchcio/tip/Why-SLA-compliance-should-be-top-of-mind-for-IT-leaders">service level agreement</a> be executed?</li> <li>What security features does the software have to protect it from cyberattacks?</li> <li>What are the pricing models -- per device and per user -- and what is the cost of maintenance?</li> <li>How is training provided?</li> <li>Is there a vendor help desk to handle problems?</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Commercial and open source cable management products"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Commercial and open source cable management products</h2> <p>Depending on the cable management requirements, commercial and open source products are available. The following two lists include examples of both types of products, in alphabetical order.</p> <h3>Commercial products</h3> <p>Examples of commercial products include the following:</p> <ul class="default-list"> <li><b>Device42</b>. Offers strong discovery features and dependency mapping. Used for enterprise-level infrastructures.</li> <li><b>netTerrain DCIM. </b>Handles a wide range of IT infrastructure requirements and delivers interactive<b> </b>visuals and detailed circuit maps.</li> <li><b>Patch Manager</b>. Offers a wide array of tools and templates to track devices. Designed for large installations in buildings, data centers and campus infrastructures. Web- and SaaS-based options are available.</li> <li><b>Sunbird DCIM</b>. Supports data center requirements while delivering active network monitoring of infrastructure attributes with a user-friendly dashboard.</li> </ul> <h3>Open source products</h3> <p>Examples of open source include the following:</p> <ul class="default-list"> <li><b>DCImanager</b>. Details cable infrastructure. Designed for large enterprises.</li> <li><b>NetBox</b>. Captures IP addresses, inventories devices and displays cable routes and rack maps. Designed for data centers and networking professionals.</li> <li><b>OpenDCIM</b>. Tracks assets and details network infrastructure. Web-based tools are designed for enterprise DCIM requirements.</li> <li><b>RackTables</b>. Details cable racks, including asset management. Tailored to SMBs.</li> <li><b>WireViz</b>. Details cable infrastructures and displays detailed visual images. Designed for network engineers.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="AI's influence on cable management"> <h2 class="section-title"><i class="icon" data-icon="1"></i>AI's influence on cable management</h2> <p>AI and machine learning are <a href="https://www.techtarget.com/searchenterpriseai/feature/Machine-learning-and-predictive-analytics-work-better-together">changing the face</a> of cable management. Their benefits include the following:</p> <ul class="default-list"> <li><b>Improved cabling capabilities.</b> Enhanced design and planning capabilities that accommodate all aspects of cabling, including its use in environmental systems, HVAC and power.</li> </ul> <ul class="default-list"> <li><b>Comprehensive performance analysis. </b>Increased performance analysis features identify and predict potential faults and provide recommendations for active maintenance.</li> <li><b>Asset management. </b>Enhanced asset tracking and management capabilities support large enterprises by extending to all parts of a network infrastructure.</li> <li><b>Threat detection. </b>Security issue identification reduces the likelihood of unauthorized access to the system and ensures the network's overall integrity.</li> <li><b>Streamlined testing. </b>Optimized testing and diagnostics highlight potential problems before they occur and monitor compliance with relevant industry standards, such as ANSI/TIA 568.</li> </ul> <p><i>Paul Kirvan, FBCI, CISA, is an independent consultant and technical writer with more than 35 years of experience in business continuity, disaster recovery, resilience, cybersecurity, GRC, telecom and technical writing. </i></p> </section> Cable management software has become an essential tool for managers keeping track of thousands of network components. Before you buy, make sure you know what you're getting. https://cdn.ttgtmedia.com/visuals/German/article/ethernet-cables-and-switches-fotolia.jpg https://www.techtarget.com/searchnetworking/tip/Network-cabling-documentation Fri, 03 Oct 2025 15:30:00 GMT Navigate networking with cable management software <p>Computers and software are often intolerant of time discrepancies. Services like Kerberos authentication rely on timestamps, so if two systems disagree on the current time, users might be denied access to essential resources.</p> <p>The Network Time Protocol is an application-layer protocol in the <a href="https://www.techtarget.com/searchnetworking/definition/TCP-IP">TCP/IP suite</a>. Its job is to synchronize time between NTP clients and designated time servers. NTP supports a stratified structure, with each layer called a <i>stratum</i>.</p> <p>Smaller environments typically only have one layer, while more complex networks might support several layers. For example, business workstations typically synchronize their time with internal time servers, while home computers typically synchronize their time with internet time servers.</p> <p>This article explains NTP configuration on Linux, macOS and Windows devices in network environments, including Active Directory (AD). It includes troubleshooting tips and a best practices list to enhance network efficiency and reliability.</p> <section class="section main-article-chapter" data-menu-title="NTP architecture"> <h2 class="section-title"><i class="icon" data-icon="1"></i>NTP architecture</h2> <p>NTP uses <a href="https://www.techtarget.com/searchnetworking/definition/UDP-User-Datagram-Protocol">UDP</a> connectionless communications for low-latency data exchanges that help prevent time drift between client and time server devices. It uses port 123/udp, so plan accordingly when managing firewall configurations.</p> <p>The stratum layers include the following:</p> <ul class="default-list"> <li><b>Stratum 0.</b> In this layer, a reference clock receives the true time from a dedicated transmitter or satellite navigation system.</li> <li><b>Stratum 1.</b> In this layer, a device directly links to a reference clock.</li> <li><b>Stratum 2.</b> In this layer, a device receives its time from a stratum 1 computer.</li> <li><b>Stratum 3.</b> In this layer, a device receives its time from a stratum 2 computer.</li> </ul> <p>A stratum can include additional layers, which creates a hierarchy with a degree of separation and reduced accuracy with each new layer.</p> <p>NTP remains a critical protocol in modern networks, especially as servers and clients remain distributed across multiple regions. It's also essential in on-premises and cloud environments.</p> </section> <section class="section main-article-chapter" data-menu-title="NTP implementations"> <h2 class="section-title"><i class="icon" data-icon="1"></i>NTP implementations</h2> <p>NTP is standard for Linux, macOS and Windows configurations, making it the ideal choice for network environments with a combination of systems. Many network devices also recognize NTP.</p> <h3>Linux systems</h3> <p>Configuring NTP on Linux systems involves editing the <span style="font-family: 'courier new', courier, monospace;">/etc/ntp.conf</span> configuration file with a text editor, such as <a href="https://www.techtarget.com/searchcloudcomputing/tip/Linux-text-editor-tips-for-cloud-admins-using-Vim-and-Nano">Vim or Nano</a>. Use the configuration file entries to direct the service to the necessary time servers, as seen below:</p> <p><span style="font-family: 'courier new', courier, monospace;">server 0.pool.ntp.org</span></p> <p><span style="font-family: 'courier new', courier, monospace;">server 1.pool.ntp.org</span></p> <p>As with other Linux configuration files, if you edit the <span style="font-family: 'courier new', courier, monospace;">/etc/ntp.conf</span> file, you'll need to restart the service using the following command:</p> <p><span style="font-family: 'courier new', courier, monospace;">systemctl restart ntpd</span></p> <p>Confirm the status of the ntpd daemon using this command:</p> <p><span style="font-family: 'courier new', courier, monospace;">ntpq -p</span></p> <p>Linux servers rarely include a GUI, but workstations might have one. The steps to configure time services through the GUI vary depending on the selected desktop environment.</p> <h3>MacOS systems</h3> <p>Configure macOS for time services by browsing to <b>System Settings > General > Date & Time</b>. Enable the <i>Set time and data automatically</i> setting and specify a target NTP server. The default server is <span style="font-family: 'courier new', courier, monospace;">time.apple.com</span>, but you can add other time servers as needed.</p> <p>Query the time server manually from the Mac's Terminal by typing this command:</p> <p><span style="font-family: 'courier new', courier, monospace;">sntp time.apple.com</span></p> <h3>Windows standalone systems</h3> <p>Like macOS, Windows time services are straightforward to configure from the GUI. Browse to <b>Control Panel > Clock and Region > Date and Time > Internet Time</b> and <i>select Synchronize with an internet time server</i>. Enter the server's address to complete the settings.</p> <p>You might prefer to use the Windows command-line or want to script your NTP configurations. Begin by opening the Terminal and displaying the current configuration:</p> <p><span style="font-family: 'courier new', courier, monospace;">w32tm /query /configuration</span></p> <p>Set a preferred NTP server with this command:</p> <p><span style="font-family: 'courier new', courier, monospace;">w32tm /config /manualpeerlist:"pool.ntp.org" /syncfromflags:manual /reliable:YES /update</span></p> <p>Don't forget to restart the service:</p> <p><span style="font-family: 'courier new', courier, monospace;">net stop w32time</span></p> <p><span style="font-family: 'courier new', courier, monospace;">net start w32time </span></p> <p>Check the service's status by typing the following command:</p> <p><span style="font-family: 'courier new', courier, monospace;">w32tm /query /status</span></p> <p>You can force an immediate time synchronization using the following command:</p> <p><span style="font-family: 'courier new', courier, monospace;">w32tm /resync /rediscover</span></p> <h3>Windows domain members</h3> <p>Configuring NTP isn't typically necessary in AD environments. Domain members automatically synchronize their time with the Domain Controller that authenticated them. All DCs synchronize their time with the Primary DC Emulator, a critical <a href="https://www.techtarget.com/searchwindowsserver/tutorial/How-to-transfer-FSMO-roles-with-PowerShell">Flexible Single Master Operations role</a> in Windows Server AD. Domain administrators configure the PDC to sync with an external time source.</p> <p>This hierarchy ensures a simple, reliable and synchronized configuration throughout the domain, which is essential to authentication services that rely on timestamps, such as Kerberos.</p> </section> <section class="section main-article-chapter" data-menu-title="Advanced NTP configurations"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Advanced NTP configurations</h2> <p>NTP has two advanced settings that require further investigation. These are polling times and the <span style="font-family: 'courier new', courier, monospace;">iburst</span> parameter.</p> <p>Polling times define the <a target="_blank" href="https://notes.networklessons.com/ntp-poll-interval" rel="noopener">intervals</a> at which the NTP client polls its specified NTP servers. The <span style="font-family: 'courier new', courier, monospace;">minpoll</span> option sets the minimum time, and <span style="font-family: 'courier new', courier, monospace;">maxpoll</span> specifies the maximum time.</p> <ul class="default-list"> <li><b><span style="font-family: 'courier new', courier, monospace;">minpoll</span>.</b> Shortest interval between polls.</li> <li><b><span style="font-family: 'courier new', courier, monospace;">maxpoll</span>. </b>Longest interval between polls.</li> </ul> <p>Time increments are exponents of 2. The default <span style="font-family: 'courier new', courier, monospace;">minpoll</span> value is 6 -- or 64 seconds -- and the usual <span style="font-family: 'courier new', courier, monospace;">maxpoll</span> setting is 10 -- which is 1024 seconds, or about 17 minutes.</p> <p>Add these values to the server entry in <span style="font-family: 'courier new', courier, monospace;">/etc/ntp.conf:</span></p> <p><span style="font-family: 'courier new', courier, monospace;">server ntp.example.com minpoll 4 maxpoll 6</span></p> <p>It's rarely necessary to modify the defaults, but some time-sensitive applications might require these settings.</p> <p>The <span style="font-family: 'courier new', courier, monospace;">iburst</span> setting speeds the initial time synchronization when the ntpd first starts. The standard setting, with no <span style="font-family: 'courier new', courier, monospace;">iburst</span> parameter set, causes the NTP client to send one query for time synchronization. However, if the specified NTP server does not respond, the NTP client delays time synchronization. The <span style="font-family: 'courier new', courier, monospace;">iburst</span> parameter causes the client to send a burst of eight packets about two seconds apart, which increases the chances of receiving a response.</p> <p>Modify the time server entry in <span style="font-family: 'courier new', courier, monospace;">/etc/ntp.conf</span> by adding the <span style="font-family: 'courier new', courier, monospace;">iburst</span> setting:</p> <p><span style="font-family: 'courier new', courier, monospace;">server ntp.example.com iburst</span></p> <p>This configuration usually matters when the system boots up. Don't confuse this setting with burst, which sends multiple queries at every polling interval. The iburst option only sends multiple queries during the initial synchronization task, which is much more efficient.</p> <p>Define polling and <span style="font-family: 'courier new', courier, monospace;">iburst </span>settings in the <span style="font-family: 'courier new', courier, monospace;">/etc/ntp.conf</span> configuration file for more efficient time management.</p> </section> <section class="section main-article-chapter" data-menu-title="Troubleshooting common NTP issues"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Troubleshooting common NTP issues</h2> <p>One configuration and troubleshooting concern involves environments with only two time servers defined. Issues arise when client devices cannot determine the correct time due to a time disagreement between the two target time servers. A third or fourth NTP server acts as a tiebreaker. This issue is sometimes called the <i>NTP two-server problem</i>.</p> <p>Avoid configurations where AD domain members -- such as Windows servers and workstations -- recognize a different time than non-domain members, such as Linux, macOS and network devices. Authentication and access problems might occur if these devices need to share resources but disagree on the current time.</p> <p>Use the following NTP commands on Linux and similar systems to troubleshoot NTP issues:</p> <ul class="default-list"> <li><b><span style="font-family: 'courier new', courier, monospace;">ntpd -d</span>. </b>Runs the ntpd in debug mode, providing useful trace information.</li> <li><b><span style="font-family: 'courier new', courier, monospace;">ntpq</span>. </b>Queries the ntpd for statistics and status data.</li> <li><b><span style="font-family: 'courier new', courier, monospace;">ntpstat</span>.</b> Displays the client's current synchronization status.</li> </ul> <p>On most Linux distributions, ntpd logs to <span style="font-family: 'courier new', courier, monospace;">/etc/messages</span> by default. However, edit the <span style="font-family: 'courier new', courier, monospace;">/etc/ntp.conf</span> file to define a dedicated log file location, such as <span style="font-family: 'courier new', courier, monospace;">/var/log/ntp.log</span>.</p> <p>Windows systems log NTP entries in Event Viewer. Browse the <b>Application Event Log</b> entries for NTP details.</p> </section> <section class="section main-article-chapter" data-menu-title="Best practices for NTP configuration"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Best practices for NTP configuration</h2> <p>NTP is a well-established and reliable part of the TCP/IP suite, so plenty of documentation exists for how to manage it. Rely on the following best practices to get the most from your NTP settings:</p> <ul class="default-list"> <li>Use the <span style="font-family: 'courier new', courier, monospace;">iburst</span> option to speed up the initial time synchronization after starting or restarting the service.</li> <li>Configure polling intervals for systems with time-sensitive applications.</li> <li>Configure multiple NTP servers. Four is the preferred number.</li> <li>Rely on AD for time management in AD deployments.</li> <li>Configure highly available, dedicated NTP sources, especially for internal network time servers that will support client devices.</li> <li>Design a consistent NTP infrastructure across your internal network. Larger environments should mimic the standard stratum layered design.</li> </ul> <p>Configure an efficient and reliable NTP environment to ensure robust time synchronization across Linux, macOS, and Windows devices. Consider integrating network devices like routers and switches into the design, too. While time management is straightforward in most networks, it's also critical.</p> <p><i>Damon Garn owns Cogspinner Coaction and provides freelance IT writing and editing services. He has written multiple CompTIA study guides, including the Linux+, Cloud Essentials+ and Server+ guides, and contributes extensively to Informa TechTarget, The New Stack and CompTIA Blogs.</i></p> </section> This guide explains NTP configuration across Linux, macOS and Windows systems. It covers architecture, troubleshooting and best practices for reliable network time synchronization. https://cdn.ttgtmedia.com/visuals/searchNetworking/infrastructure/networking_article_008.jpg https://www.techtarget.com/searchnetworking/tip/Network-timing-Everything-you-need-to-know-about-NTP Wed, 17 Sep 2025 11:37:00 GMT A configuration guide to Network Time Protocol <p>The application layer is at Layer 7, the top of the Open Systems Interconnection (OSI) communications model. It ensures that an application can communicate with other applications on different computer systems and networks.</p> <p>The application layer isn't an application. Instead, it's a component within an application that controls the communication method to other devices. It's an <a href="https://www.techtarget.com/whatis/definition/abstraction">abstraction</a> layer service that masks the rest of the application from the transmission process.</p> <p>The application layer relies on all the layers below it to complete its process. At this stage, the data or the application is presented in a visual form that the user can understand.</p> <section class="section main-article-chapter" data-menu-title="How does the application layer work?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How does the application layer work?</h2> <p>The application layer lets users and software interact with <a href="https://www.techtarget.com/searchnetworking/answer/Common-network-services-and-their-functions">network services</a>. It operates on a client-server model, where the client, such as a user's device, sends requests to a server, which responds with the requested data.</p> <p>The application layer doesn't handle data transport but ensures data -- such as websites, streamed videos and downloaded files -- is presented correctly. It is the gateway for applications, such as web browsers and email clients, to communicate with an underlying network. This ensures data is sent or received in a usable format.</p> <p>For example, when a domain name is typed into a browser, the application layer translates it into a request that the network can process.</p> </section> <section class="section main-article-chapter" data-menu-title="Functions of the application layer"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Functions of the application layer</h2> <p>The application layer handles the following functions:</p> <ul class="default-list"> <li>Ensures the receiving device is identified, reachable and ready to accept data.</li> <li>When appropriate, enables <a href="https://www.techtarget.com/searchsecurity/definition/authentication">authentication</a> between devices for an extra layer of network security.</li> <li>Confirms that necessary communication interfaces exist, such as an Ethernet or Wi-Fi interface in the sender's computer.</li> <li>Gets both ends to agree on error recovery procedures, <a href="https://www.techtarget.com/searchdatacenter/definition/integrity">data integrity</a> and privacy.</li> <li>Determines protocol and data syntax rules at the application level.</li> <li>Presents the data to the user application on the receiving end.</li> </ul> <p>Two types of software provide access to the network within the application layer:</p> <ol class="default-list"> <li>Network-aware applications, such as email.</li> <li>Application-level services, such as file transfer or print spooling.</li> </ol> <div class="youtube-iframe-container"> <iframe id="ytplayer-0" src="https://www.youtube.com/embed/jlp8HL_iIqo?si=smd3vdQlrzr-LKP-?autoplay=0&modestbranding=1&rel=0&widget_referrer=null&enablejsapi=1&origin=https://www.techtarget.com" type="text/html" height="360" width="640" frameborder="0"></iframe> </div> <p></p> </section> <section class="section main-article-chapter" data-menu-title="How the OSI model works"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How the OSI model works</h2> <p>Before the creation of the OSI model, applications ran on separate systems. They used different network technologies that couldn't communicate or exchange information.</p> <p>To solve that issue, the <a href="https://www.techtarget.com/searchdatacenter/definition/ISO">International Organization for Standardization</a> designed a layered approach to accommodate technological changes. It breaks down inconsistencies to foster greater information exchange.</p> <p>Devices like routers and switches have OSI protocols embedded in their firmware to facilitate computer networking among different systems and network infrastructures. Applications contain protocols to facilitate the data transfer process with lower OSI layers.</p> <p>Each layer of the OSI model handles different network functions. They transfer specific information between upper and lower layers during data processing and information exchange.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/networking-osi_layers_application.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/networking-osi_layers_application_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/networking-osi_layers_application_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/networking-osi_layers_application.png 1280w" alt="List of the OSI model's layers, showing where the application layer is." height="500" width="519"> <figcaption> <i class="icon pictures" data-icon="z"></i>The application layer of the OSI model facilitates communication among applications on different computer systems. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p></p> </section> <section class="section main-article-chapter" data-menu-title="OSI layers and their functions"> <h2 class="section-title"><i class="icon" data-icon="1"></i>OSI layers and their functions</h2> <p>The seven OSI layers are the following:</p> <ol class="default-list"> <li><b>Physical layer.</b> In the <a href="https://www.techtarget.com/searchnetworking/definition/physical-layer">physical layer</a>, devices such as a local area network or router physically link to a network.</li> <li><b>Data link layer.</b> The <a href="https://www.techtarget.com/searchnetworking/definition/Data-Link-layer">data link layer</a> defines how data is transferred over a connecting link.</li> <li><b>Network layer.</b> The <a href="https://www.techtarget.com/searchnetworking/definition/Network-layer">network layer</a> determines how messages move across a network, such as end-to-end movement of data packets using logical addresses.</li> <li><b>Transport layer.</b> The <a href="https://www.techtarget.com/searchnetworking/definition/Transport-layer">transport layer</a> facilitates error recovery and reorders data packets that are in the wrong sequence.</li> <li><b>Session layer.</b> The <a href="https://www.techtarget.com/searchnetworking/definition/Session-layer">session layer</a> manages all phases of a session, including setup, in-process control functions and message takedown, and it supports concurrent transmission of multiple bidirectional messages.</li> <li><b>Presentation layer.</b> The <a href="https://www.techtarget.com/searchnetworking/definition/presentation-layer">presentation layer</a> supports message formatting and encryption.</li> <li><b>Application layer.</b> This layer facilitates communication with applications running on other computers.</li> </ol> </section> <section class="section main-article-chapter" data-menu-title="Application layer protocols"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Application layer protocols</h2> <p>The application layer was developed with the following two sublayers:</p> <ul class="default-list"> <li><b>Common application service element.</b> CASE provides services for the application layer and requests services from the session layer. Its activities include remote operation control and data transfer. CASE services apply to a variety of application requirements.</li> <li><b>Specific application service element. </b>SASE provides application-specific services, such as file transfer, <a href="https://www.techtarget.com/searchsecurity/definition/remote-access">remote database access</a>, application management information and transaction processing.</li> </ul> <p>Early application layer protocols the Internet Engineering Task Force specified in <a target="_blank" href="https://datatracker.ietf.org/doc/html/rfc1233" rel="noopener">Request for Comments 1233</a> included the following four protocols that are still in use:</p> <ul class="default-list"> <li><b>File Transfer Protocol.</b> <a href="https://www.techtarget.com/searchnetworking/definition/File-Transfer-Protocol-FTP">FTP</a> handles file transfer activities.</li> <li><b>Simple Mail Transfer Protocol.</b> <a href="https://www.techtarget.com/whatis/definition/SMTP-Simple-Mail-Transfer-Protocol">SMTP</a> handles the movement of electronic mail.</li> <li><b>Domain Name System.</b> <a href="https://www.techtarget.com/searchnetworking/definition/domain-name-system">DNS</a> maps the name used for a website to its IP address.</li> <li><b>Simple Network Management Protocol.</b> <a href="https://www.techtarget.com/searchnetworking/definition/SNMP">SNMP</a> provides remote host management.</li> </ul> <p>The following are examples of well-known application layer protocols in use today:</p> <ul class="default-list"> <li><a href="https://www.techtarget.com/whatis/definition/Bitcoin">Bitcoin</a> for digital currency.</li> <li><a href="https://www.techtarget.com/whatis/definition/HTTP-Hypertext-Transfer-Protocol">Hypertext Transfer Protocol</a> for message communications.</li> <li>H.323 for packet-based communications, such as <a href="https://www.techtarget.com/searchunifiedcommunications/definition/VoIP">voice over IP</a>;</li> <li><a href="https://www.techtarget.com/searchmobilecomputing/definition/LDAP">Lightweight Directory Access Protocol</a> for queries of user information.</li> <li><a href="https://www.techtarget.com/searchenterprisedesktop/definition/Network-File-System">Network File System</a> for data storage and retrieval from various media.</li> <li><a href="https://www.techtarget.com/searchapparchitecture/definition/Remote-Procedure-Call-RPC">Remote Procedure Call</a> to execute a procedure or <a href="https://www.techtarget.com/whatis/definition/routine">subroutine</a> on a different system or network; and</li> <li>X.400 Message Handling Service Protocol that facilitates the transfer of email among compatible systems.</li> </ul> <p>Many communications protocols and interface methods have been developed based on the OSI model. Communication with remote hosts is common and uses a variety of web browsers, the application layer and its six complementary layers.</p> </section> <section class="section main-article-chapter" data-menu-title="Who uses the application layer?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Who uses the application layer?</h2> <p>Several IT professionals use the application layer as part of their jobs. The most common include the following:</p> <ul class="default-list"> <li><b>Software engineers.</b> Their programs must ensure data flows correctly between clients and servers via the application layer.</li> <li><b>Systems architects.</b> They plan the implementation of network services, ensuring the application layer integrates with lower-level infrastructure.</li> <li><b>Web developers.</b> Their web designs rely on the application layer.</li> <li><b>Cybersecurity analysts.</b> They analyze vulnerabilities in the application layer, such as vulnerabilities tied to domain misuse and protocol exploits.</li> <li><b>Network administrators.</b> They monitor and secure the layer against targeted network attacks.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="OSI vs. Transmission Control Protocol/Internet Protocol"> <h2 class="section-title"><i class="icon" data-icon="1"></i>OSI vs. Transmission Control Protocol/Internet Protocol</h2> <p>The <a href="https://www.techtarget.com/searchnetworking/answer/What-is-the-difference-between-OSI-model-and-TCP-IP-other-than-the-number-of-layers">OSI model and TCP/IP models are often compared</a>. In the OSI model, the application layer is a distinct, topmost layer. It sits above the presentation and session layers, providing network services to end-user applications. IT demarcates tasks. For instance, in the OSI model, the application layer handles protocols such as HTTP and SMTP, while the lower layers manage data transport.</p> <p>The TCP/IP model combines the application, presentation and session layers into one application layer. This version still allows browsing, file transfers and other client-server interactions, but it doesn't differentiate the layers. The TCP/IP model prioritizes practical implementation over conceptual clarity, making it a popular option for modern internet infrastructure.</p> <p><i>Find out about the </i><a href="https://www.techtarget.com/searchnetworking/feature/12-common-network-protocols-and-their-functions-explained"><i>common networking protocols</i></a><i> you should know and understand.</i></p> </section> The application layer is at Layer 7, the top of the Open Systems Interconnection (OSI) communications model. It ensures that an application can communicate with other applications on different computer systems and networks. https://cdn.ttgtmedia.com/visuals/digdeeper/6.jpg https://www.techtarget.com/searchnetworking/definition/Application-layer Fri, 12 Sep 2025 09:00:00 GMT What is the application layer? <p>Any really successful cabling project starts with knowing the requirements for the cable needed. The speeds required, the distances to be covered and the need for power all will determine which type of cable -- Cat5e, Cat6A, Cat7 or Cat8 -- to use or where to pull fiber, copper or even special-circumstances cables.</p> <p>The specifications on each cable type determine its capabilities. Network professionals must pay attention to the cable specifications to avoid major mistakes such as wrapping cables around an electrical transformer or making a hairpin turn. Important cable specifications to focus on include the following:</p> <ul class="default-list"> <li>The maximum length of cable run for reliable data delivery.</li> <li>The cable bend radius, or how tightly it can bend around a corner without hurting performance or reliability.</li> <li>The <a href="https://www.techtarget.com/searchnetworking/definition/patch-panel">patch panel</a> specifications.</li> </ul> <section class="section main-article-chapter" data-menu-title="Best practices for network cable management"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Best practices for network cable management</h2> <p>Network engineers should consider <a href="https://www.techtarget.com/searchnetworking/tip/Network-cabling-documentation">cabling best practices</a> to simplify management once installed. Following these steps helps with network maintenance, troubleshooting and simplifies the process of implementing infrastructure upgrades in the future.</p> <h3>1. Corral the cables</h3> <p>In a data center, keep cables out of the traffic path -- from floor level up to head height -- and out of the workspaces behind racked equipment. Use cable trays <a href="https://www.techtarget.com/searchdatacenter/tip/Pick-a-data-center-layout-Raised-floors-vs-overhead-cabling">overhead or under a raised floor</a> to get from row to row or from one rack to a non-adjacent one. For adjacent racks, use cable supports and organizers on the sides and backs of racks.</p> <p>At the equipment end, whether it's a server or switch, leave a little slack in the patch cables to easily plug and unplug from the equipment. The same advice goes for patch panels.</p> <p>Outside data centers, secure cables in closets, passages through walls and above drop ceilings using metal straps, plastic zip-ties or Velcro. Cable races, trays or conduits are also helpful for keeping the cables from snagging on other infrastructure and vice versa. This makes it easier to trace a cable through the physical environment for troubleshooting and repairs.</p> <h3>2. Mind the weight</h3> <p>Bundles of network cables can be quite heavy. If cables aren't lying on the floor, always provide adequate support that can double as cable organizers in some cases. Supply support with a significant safety margin -- more than necessary for the current cable set -- in anticipation of adding more or heavier cables.</p> <p>Weight can be a pressing concern when upgrading older cables. Modern cables that support Power over Ethernet (PoE) are often significantly heavier than the older cables they replace. This can be a problem with overhead <a href="https://www.techtarget.com/searchdatacenter/definition/raceway">raceways</a> and cable supports in data centers, wiring closets or above raised ceilings.</p> <h3>3. Differentiate with colors and labels</h3> <p>Every cable has two ends, and it's critical to handle the same cable at both ends. To simplify this, label both ends with a number or an <a href="https://www.fs.com/blog/proper-cable-labeling-guidelines-13642.html" target="_blank" rel="noopener">alphanumeric code</a> that embeds information about the run, such as the closet it originates in. Cable codes don't have to be unique overall, but they should be unique with respect to the places where the run ends, such as a closet or the data center.</p> <p>It's often not useful to label cable ends with anything more specific than a closet identifier in a cable labeling code. Some network pros want to embed hardware or port identifiers, but these components are subject to change and would require relabeling. It's better to use a component that is less likely to change, such as the wiring closet where a cable ends.</p> <p>Color coding is another way for network staff to easily identify a cable during troubleshooting or <a href="https://www.techtarget.com/searchdatacenter/definition/moves-adds-and-changes-MAC">moves, adds and changes</a>, especially in a data center. Cables for data connections can be one color, storage network connections another and KVM connections a third.</p> <p>The drawback to color coding is it's harder to freely reuse a patch cable. To avoid that, use colored tape near the cable ends instead of colored cables. Pair labeling and color-coding by printing the cable code on a colored label.</p> <h3>4. Document everything</h3> <p>It's hard to manage cables if their locations are unknown. Regardless of the labeling and color-coding system a team settles on, they should clearly spell out and maintain the standards in central, shared spaces with other organizational <a href="https://www.techtarget.com/searchnetworking/tutorial/Network-documentation-and-auditing">standards and practices documentation</a>.</p> <p>In areas where cables run out of sight, such as under a raised floor, the team should also ensure they have maps or diagrams that clearly show where the cables run. It's sometimes difficult to find cables or see much under full racks of equipment, so it's important to have documentation that references labels and colors. This is also relevant for when cables run through a conduit between floors or in a buried conduit between buildings.</p> <p>To ensure documentation stays current, both IT and facilities teams should include updating cabling maps and documentation in their change management, construction and renovation processes.</p> </section> <section class="section main-article-chapter" data-menu-title="Cable management practices to avoid"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Cable management practices to avoid</h2> <p>Bad cable management practices are the inverse of best practices. Network professionals should avoid the following when managing network cables:</p> <ul class="default-list"> <li><b>Lack of cable use case knowledge. </b>When network professionals don't understand the use cases for a <a href="https://www.techtarget.com/searchnetworking/tutorial/Network-cable-history-and-fundamentals-Cabling-tips-for-network-professionals-lesson-1">specific type of cable</a>, they struggle to identify which cables are most appropriate for different situations.</li> <li><b>Improper cable routing. </b>Improper cable placement or routing can complicate cable management and create safety hazards. Don't run cables loosely from row to row or rack to rack, as this can add stress to the cables and lead to malfunctions. Sharply bent cables can also fail. Don't run cables across the fronts and backs of equipment in racks. Instead, use the cable management races on the sides.</li> <li><b>Failure to follow plans.</b> Having a plan for labels and color-coding is not enough; network professionals must also follow it.</li> <li><b>Outdated documentation.</b> Network professionals must update documentation during moves, adds, changes, construction and renovation.</li> <li><b>Crowded trays or conduits.</b> It can be difficult to access cables in trays and conduits filled beyond their capacity. In addition, cable trays that aren't supported well enough might not stay in place under load.</li> <li><b>Inadequate cable placement. </b>Not tracking where cables terminate or originate in long conduits can create network management and maintenance problems. Ensure cables aren't bent -- which can eventually malfunction -- or coiled around sources with <a href="https://www.techtarget.com/searchmobilecomputing/definition/electromagnetic-interference">electromagnetic interference</a>, such as elevator motors.</li> </ul> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/network_cable_management-f.jpg"> <img data-src="https://www.techtarget.com/rms/onlineimages/network_cable_management-f_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/network_cable_management-f_mobile.jpg 960w,https://www.techtarget.com/rms/onlineimages/network_cable_management-f.jpg 1280w" alt="Image comparing bad vs. good cable management." data-credit="CONNECT IMAGES (left), GENKUR (right)" height="188" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>Compare bad cable management (left) vs. good cable management (right). </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="Cable management optimization strategies"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Cable management optimization strategies</h2> <p>In addition to following best practices, network teams should also focus on other strategies that enhance their approaches to cable management. For example, rightsizing, along with routine spot checks and audits, can help network teams proactively manage, monitor and administer their networks.</p> <h3>Rightsizing</h3> <p>While cable specifications can indicate the maximum length of a particular type of cable, they can't show the optimal length for a network's specific requirements. Rightsizing is the process of gathering data and adjusting infrastructure components based on expected needs It helps admins identify performance requirements, plan for future scalability efforts and upgrades, and account for costs.</p> <p>A successful <a href="https://www.techtarget.com/searchnetworking/tip/Network-design-principles-for-effective-architectures">network design</a>, influenced by a proper rightsizing approach, strikes the right balance between conserving materials and flexibility. For example, organizing cables to be only as long as needed enables network teams to have enough room to make minor changes to the network over time.</p> <p>Examples of rightsizing practices include the following:</p> <ul class="default-list"> <li>Relocate one end of a cable to make room for another rack.</li> <li>Position cables from one side of a wall to another.</li> <li>Route the middle of a cable to make way for new installations, such as pipes, ventilation conduits or sprinkler systems.</li> </ul> <p>When network teams install cables, it's important that they leave some slack for cable repositioning. This prevents them from having to re-pull a cable or insert a switch or repeater into the run.</p> <h3>Spot checks and audits</h3> <p>It's great if network teams have all the documentation about their networks, especially when required updates are built into standard processes. However, to keep documentation accurate and useful, network teams should regularly audit the cabling and documentation together.</p> <p>Pick a space and ensure the cabling is up to standards and the documentation is accurate. This can be a separate maintenance process or piggybacked on other trouble tickets. Although audits should be regular, they can be random or based on a plan and schedule.</p> <h3>Consider wireless connectivity</h3> <p>Organizations that want to reduce the number and weight of cables can consider switching their networks to wireless endpoints outside the data center. This option might be especially useful in endpoint-dense locations such as open-plan office floors and classrooms.</p> <p>However, cabling is still necessary in wireless networks. Wireless endpoints still need connectivity and PoE. Other endpoints, such as big, shared printers, still remain wired.</p> <p><i>John Burke is CTO and a research analyst at Nemertes Research. Burke joined Nemertes in 2005 with nearly two decades of technology experience. He has worked at all levels of IT, including as an end-user support specialist, programmer, system administrator, database specialist, network administrator, network architect and systems architect.</i></p> </section> When organizing cable clutter, network engineers should follow best practices, such as labeling, using cable ties and maintaining proper documentation, while avoiding trip hazards. https://cdn.ttgtmedia.com/visuals/searchUnifiedCommunications/implementing_systems/unifiedcommunications_article_004.jpg https://www.techtarget.com/searchnetworking/tutorial/Ten-cabling-tips-in-10-minutes Fri, 05 Sep 2025 09:00:00 GMT A network cable management guide <p>Fault management is the component of network management that detects, isolates and fixes problems. When properly implemented, fault management keeps connectivity, applications and services running at an optimal level, provides fault tolerance and minimizes downtime. Fault management systems<i> </i>are platforms or tools designed specifically for this purpose.</p> <p>Faults result from <a href="https://www.techtarget.com/searchnetworking/answer/What-are-the-3-most-common-network-issues-to-troubleshoot">malfunctions or events</a> that interfere with, degrade or obstruct service delivery. Examples of faults include hardware failure, connectivity loss or port status change. Once the fault management platform detects a fault, it notifies the administrator and any additional authorized or designated parties with an alarm or alert.</p> <p>Many platforms forward alerts via email, text or a mobile app. These notifications are viewable in the fault management system's GUI. Network administrators can also configure fault management systems to automatically fix or prevent certain events using programs and scripts.</p> <p>Fault management is one component of <a href="https://www.techtarget.com/searchnetworking/definition/FCAPS">FCAPS</a> (fault management, configuration, accounting, performance and security), a <a href="https://www.techtarget.com/searchnetworking/answer/What-are-the-5-different-types-of-network-management">network management framework</a> established by the International Organization for Standardization.</p> <section class="section main-article-chapter" data-menu-title="Fault management functions"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Fault management functions</h2> <p>Network fault management comprises a variety of functions to keep the network operational. Fault management systems perform the following actions:</p> <ul class="default-list"> <li>Define thresholds for potential failure conditions.</li> <li>Monitor system status and usage levels while scanning for threats, such as viruses and <a href="https://www.techtarget.com/searchsecurity/definition/Trojan-horse">Trojans</a>.</li> <li>Provide general diagnostics.</li> <li>Control system elements remotely -- including workstations and servers -- from a single location.</li> <li>Trace the locations and notify administrators and users of impending and actual malfunctions.</li> <li>Correct potential problem-causing conditions and fix malfunctions automatically.</li> <li>Log system status and actions taken.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Types of fault management"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Types of fault management</h2> <p>Two types of network fault management exist: active and passive.</p> <h3>Active fault management</h3> <p>Active fault management uses various tools to continually query devices and determine their status. Some of these strategies include using <a href="https://www.techtarget.com/searchnetworking/definition/ping">ping</a> or checking port for Transmission Control Protocol and User Datagram Protocol.</p> <p>Active fault management is akin to a person asking, "How are you?" to every person in a room at repeated intervals. This enables the system to identify and rectify potential issues in real time, sometimes before they even become problems. The trade-off, however, is more network chatter.</p> <h3>Passive fault management</h3> <p>Passive fault management systems monitor network environments for events that indicate whether a fault or failure has occurred. This information comes from many sources, including error logs or <a href="https://www.techtarget.com/searchnetworking/definition/SNMP">Simple Network Management Protocol</a> traps.</p> <p>Passive fault management is akin to a person who quietly listens until someone calls out for help. This type of fault management is more conservative with resource use. However, the drawback is that it might not discover faults until it's too late.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/networking-fault_management.png"> <img data-src="https://www.techtarget.com/rms/onlineImages/networking-fault_management_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/networking-fault_management_mobile.png 960w,https://www.techtarget.com/rms/onlineImages/networking-fault_management.png 1280w" alt="Chart that depicts the fault management workflow." height="318" width="520"> <figcaption> <i class="icon pictures" data-icon="z"></i>Fault management systems typically operate in this workflow. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="Fault management process"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Fault management process</h2> <p>The fault management process used in commercial platforms might vary slightly among different vendors. However, all fault management systems typically follow the same lifecycle:</p> <ol class="default-list"> <li><b>Fault detection.</b> The system discovers that something interrupted service delivery, or its performance has degraded.</li> <li><b>Fault diagnosis and isolation.</b> The system identifies the source of the fault -- such as a component failure or power outage -- and its location in the network topology.</li> <li><b>Event correlation and aggregation.</b> A single fault can cause multiple alarms. Fault management systems often group related events for administrators and provide a <a href="https://www.techtarget.com/searchitoperations/definition/root-cause-analysis">root cause analysis</a>.</li> <li><b>Restoration of service.</b> The network management system automatically executes any preconfigured scripts or programs to run services as soon as possible.</li> <li><b>Problem resolution.</b> The system corrects, repairs or replaces the source of the fault. In some cases, manual intervention might be necessary.</li> </ol> </section> Fault management is the component of network management that detects, isolates and fixes problems. https://cdn.ttgtmedia.com/visuals/digdeeper/6.jpg https://www.techtarget.com/searchnetworking/definition/fault-management Thu, 21 Aug 2025 09:00:00 GMT What is fault management? <p>Point-to-Point Protocol over Ethernet (PPPoE) is a <a href="https://www.techtarget.com/searchnetworking/definition/protocol">network protocol</a> that facilitates communication between network endpoints. PPPoE encapsulates Point-to-Point Protocol frames inside <a href="https://www.techtarget.com/searchnetworking/definition/Ethernet">Ethernet</a> frames, offering the same benefits as <a href="https://www.techtarget.com/searchnetworking/definition/PPP">PPP</a>, while providing connectivity across Ethernet networks.</p> <p>With PPPoE, internet service providers (ISPs) can manage multiple client systems, authenticate their access to their services and track customer data usage. PPPoE also supports services such as data <a href="https://www.techtarget.com/searchsecurity/definition/encryption">encryption</a> and compression.</p> <section class="section main-article-chapter" data-menu-title="What is PPPoE used for?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>What is PPPoE used for?</h2> <p>PPPoE is commonly used by ISPs to deliver internet access services to their customers, typically over broadband connections. Providers offering Digital Subscriber Line (DSL) services implement PPPoE extensively. They use PPPoE to connect multiple hosts on a single Ethernet local area network to a remote site using a common device, such as a cable or DSL modem. The protocol can also support wireless connections to the Internet.</p> <p>UUNET, Redback Networks (now Ericsson) and RouterWare (now Wind River Systems) developed PPPoE to address PPP limitations and provide an option for organizations that relied on common <a href="https://www.techtarget.com/searchnetworking/definition/customer-premises-equipment">customer premises equipment</a> to support multihost environments. In February 1999, the Internet Society helped to formalize PPPoE by publishing Request for Comments 2516. This informational specification describes PPPoE and how to build PPP sessions and encapsulate PPP <a href="https://www.techtarget.com/searchnetworking/definition/packet">packets</a> over Ethernet.</p> <div class="youtube-iframe-container"> <iframe id="ytplayer-0" src="https://www.youtube.com/embed/i2qiNAVfQRw?autoplay=0&modestbranding=1&rel=0&widget_referrer=null&enablejsapi=1&origin=https://www.techtarget.com" type="text/html" height="360" width="640" frameborder="0"></iframe> </div> </section> <section class="section main-article-chapter" data-menu-title="How does PPPoE work?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How does PPPoE work?</h2> <p>Ethernet and PPP do not provide native support for each other, yet they both offer essential benefits for supporting multihost network environments. PPPoE bridges the gap between Ethernet and PPP by facilitating a point-to-point relationship between network peers. A multihost Ethernet environment can use PPPoE to open PPP sessions to multiple destinations using one or more <a href="https://www.techtarget.com/searchsecurity/definition/bridge">bridging</a> modems.</p> <p>Like Ethernet and PPP, PPPoE operates at the network access layer in <a href="https://www.techtarget.com/searchnetworking/definition/TCP-IP">TCP/IP</a> and at the data link layer in the Open Systems Interconnection <u>(<a href="https://www.techtarget.com/searchnetworking/definition/OSI">OSI</a>)</u> model. The protocol is intended for use with remote access broadband technologies that offer a bridged Ethernet topology. With PPPoE, service providers can take advantage of Ethernet's cost-effective benefits and still maintain the session abstraction, access control and billing functionality available to PPP.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/networking-osi_vs_tcp-ip_model_table.jpg"> <img data-src="https://www.techtarget.com/rms/onlineImages/networking-osi_vs_tcp-ip_model_table_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/networking-osi_vs_tcp-ip_model_table_mobile.jpg 960w,https://www.techtarget.com/rms/onlineImages/networking-osi_vs_tcp-ip_model_table.jpg 1280w" alt="A chart comparing the access layers for OSI and TCP/IP." height="284" width="520"> <figcaption> <i class="icon pictures" data-icon="z"></i>PPPoE functions at the OSI model's data link layer and TCP/IP model's network access layer. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>PPPoE communications are carried out in two stages: PPPoE discovery and PPP session. During the PPPoE discovery stage, the client system establishes a communication channel with an access concentrator (AC) -- a PPPoE server that negotiates and authenticates the connections with PPPoE clients. For example, a service provider might maintain multiple ACs to deliver internet access services to its customers.</p> <p>When a client attempts to initiate a session with an AC, the client and AC enter into the following four-step discovery process in which specific packet types are exchanged:</p> <ol class="default-list"> <li>The client initiates communication by transmitting a PPPoE Active Discovery Initiation (PADI) packet that includes a request for service.</li> <li>When an AC receives the PADI, it responds by sending a PPPoE Active Discovery Offer (PADO) packet that contains its name and other details about the offered service.</li> <li>In response to the PADO, the client sends a PPPoE Active Discovery Request (PADR) packet to the AC -- in effect, to accept the service. If the client receives PADOs from multiple ACs, it selects one based on the name or services offered.</li> <li>When the AC receives the PADR, it sends a PPPoE Active Discovery Session-confirmation, or PADS packet, confirming the connection and providing a session ID used throughout the session.</li> </ol> <p>After the discovery stage is complete and the connection has been established, the client and AC move on to the PPP session stage. During the session stage, point-to-point communications between the client and AC are carried out like any PPP encapsulation. The Ethernet packets themselves are sent unicast.</p> <p>During the session, the AC or client can send a PPPoE Active Discovery Termination (PADT) packet to end the session. When the client or AC receives the PADT, no further PPP traffic is allowed during that session.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/pppoe_discovery_session_processes-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/pppoe_discovery_session_processes-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/pppoe_discovery_session_processes-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/pppoe_discovery_session_processes-f.png 1280w" alt="An image showing the five steps in the PPPoE discovery/session process." height="258" width="559"> <figcaption> <i class="icon pictures" data-icon="z"></i>When a client initiates a session, it and the account concentrator follow a five-step PPPoE discovery process, sending and receiving specific packet types. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="How is PPPoE configured?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How is PPPoE configured?</h2> <p>Some ISPs supply their customers with broadband modems with the already configured PPPoE connections. In some cases, however, administrators might need to set up the connections manually. For this, they must know the PPPoE username, password and maximum transmission unit (<a href="https://www.techtarget.com/searchnetworking/definition/maximum-transmission-unit">MTU</a>) size. The ISP should provide the customer with the username and password, but administrators are responsible for the MTU sizing.</p> <p>Networks must be configured with the correct MTU size to work properly. The size is specified in octets -- 8-bit bytes -- and determines the maximum size packet or frame that can be sent across a network. TCP uses MTU when transmitting packets between devices connected to the internet.</p> <p>An MTU size that is too large might result in retransmissions if the packet encounters a <a href="https://www.techtarget.com/searchnetworking/definition/router">router</a> that cannot handle the packet size. An MTU size that is too small can result in more header overhead and a greater number of acknowledgments that need to be sent and received. The recommended MTU for a network interface connected to a PPPoE network is generally a maximum of 1492.</p> <p>There might also be times when users need to configure PPPoE connections directly from their computers, such as when a bridging modem is set up for passthrough PPPoE connectivity. In this case, users must manually configure the PPPoE connections.</p> <p>Fortunately, major operating systems, such as macOS, <a href="https://www.techtarget.com/searchdatacenter/definition/Linux-operating-system">Linux</a> and Windows, include native PPPoE support, so setting up the connection is fairly straightforward. However, users need the PPPoE account information -- service name, username and password -- which the ISP typically provides. Once they set up their connections, they should not need to bother with it again, unless they upgrade their systems or perform other operations that affect the connection.</p> </section> <section class="section main-article-chapter" data-menu-title="Benefits and drawbacks of PPPoE"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Benefits and drawbacks of PPPoE</h2> <p>ISPs and clients use PPPoE for the following reasons:</p> <ul class="default-list"> <li><b>Centralized authentication.</b> PPPoE clients can be centrally authenticated using a Remote Authentication Dial-In User Service, or RADIUS, server, making account and access management easier.</li> <li><b>Dynamic IP addressing.</b> IP address assignment to PPPoE clients can be dynamic using a central pool of available <a href="https://www.techtarget.com/whatis/definition/IP-address-Internet-Protocol-Address">IP addresses</a>.</li> <li><b>Session management.</b> Multiple sessions can be created and managed over a single physical connection.</li> <li><b>Broad support.</b> Windows, macOS and Linux all support PPPoE.</li> <li><b>Bandwidth management.</b> ISPs can optimize bandwidth by managing speed and allotment to PPPoE clients.</li> <li><b>Security.</b> IP security features, such as authentication and encryption, are easily implemented across an Ethernet network.</li> </ul> <p>PPPoE does, however, have the following drawbacks:</p> <ul class="default-list"> <li><b>Complexity.</b> PPPoE must be manually configured, requiring users to have strong familiarity and experience with network protocols.</li> <li><b>Unicast connections.</b> PPPoE supports unicast connections, which can impair both efficiency and scalability.</li> <li><b>Fragmentation potential.</b> PPPoE <a href="https://datatracker.ietf.org/doc/html/rfc4638" target="_blank" rel="noopener">reduces the MTU</a> from the Ethernet standard of 1500 bytes to 1492, possibly creating fragmentation issues.</li> <li><b>Lack of native support for multiuser environments.</b> PPP was created for point-to-point connections, not multiuser networks.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="PPPoE vs. DHCP"> <h2 class="section-title"><i class="icon" data-icon="1"></i>PPPoE vs. DHCP</h2> <p>Dynamic Host Configuration Protocol (<a href="https://www.techtarget.com/searchnetworking/definition/DHCP">DHCP</a>) is often compared to PPPoE or mentioned within the same context. DHCP is a communications protocol that runs at the TCP/IP application layer. It lets network administrators centrally manage and automate the assignment of IP addresses across a network. It also enables them to monitor and distribute IP addresses from a central point and automatically send new IP addresses when computers plug into other network locations.</p> <p>DHCP allocates unique IP addresses to network devices so that data packets can be delivered back and forth. The DHCP architecture is typically made up of DHCP clients, DHCP servers and DHCP relay agents. Without DHCP, network administrators must manually configure IP addresses when adding or moving devices from one <a href="https://www.techtarget.com/searchnetworking/definition/subnet">subnet</a> to another -- or devise another option.</p> <p>Unlike DHCP, PPPoE encapsulates network traffic based on credentialed access. Once a session is established, IP addresses can be assigned to client devices. PPPoE also includes authentication capabilities that enable ISPs to control and monitor access. However, PPPoE must be configured correctly before users can connect to the internet.</p> <p>In general, PPPoE serves a much different purpose from DHCP. It facilitates authenticated PPP communications on an Ethernet network, whereas DHCP dynamically allocates IP addresses without requiring authentication.</p> </section> <section class="section main-article-chapter" data-menu-title="PPPoE troubleshooting steps"> <h2 class="section-title"><i class="icon" data-icon="1"></i>PPPoE troubleshooting steps</h2> <p>The following are several good go-to steps for troubleshooting PPPoE implementations:</p> <ul class="default-list"> <li><b>ID address assignment failure.</b> A PPP negotiation failure can result in no IP address being assigned. Reboot the client device and modem or router.</li> <li><b>Authentication failure.</b> This is usually caused by incorrect credentials. Verify PPPoE username and password with the ISP.</li> <li><b>Slow speed.</b> If PPPoE is below the speed specified in the plan, verify the mode and bandwidth settings in the modem's and router's administrative interfaces.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="PPPoE best practices"> <h2 class="section-title"><i class="icon" data-icon="1"></i>PPPoE best practices</h2> <p>Keep the following best practices in mind when setting up PPPoE:</p> <ul class="default-list"> <li><b>Manage traffic.</b> To prevent overload, limit the number of connected devices on a PPPoE connection.</li> <li><b>Enable keepalive.</b> Keepalive manages connection status by restarting any link that goes idle.</li> <li><b>Do regular firmware updates.</b> To prevent security issues, do regular firmware updates on modems, routers and other PPPoE devices.</li> <li><b>Reboot regularly.</b> Reboot modems and routers regularly to prevent accumulating compounding issues.</li> </ul> <p><em>Port numbers are an important way to identify and direct network traffic to specific applications or services running on network-connected devices. Learn about the <a href="https://www.techtarget.com/searchnetworking/definition/port-number">different types of port numbers and their uses</a>.</em></p> </section> Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol that facilitates communication between network endpoints. https://cdn.ttgtmedia.com/visuals/digdeeper/5.jpg https://www.techtarget.com/searchnetworking/definition/PPPoE Wed, 20 Aug 2025 09:00:00 GMT What is Point-to-Point Protocol over Ethernet (PPPoE)? <p>Synchronous Optical Network (SONET) is a North American standardized digital communication protocol for synchronous data transmission over <a href="https://www.techtarget.com/searchnetworking/definition/fiber-optics-optical-fiber">optical fibers</a>. In other words, SONET transmits and <a href="https://www.techtarget.com/searchnetworking/definition/multiplexing">multiplexes</a> multiple data streams across a fiber optic cable.</p> <p>The American National Standards Institute (ANSI) developed SONET for public telephone networks in the 1980s. Today, it acts as a standard for digital networks to enable and interconnect with existing conventional transmission systems. This enables them to take advantage of optical media through tributary attachments.</p> <p>Backbone carrier networks typically use SONET. Telecom operators share data over a line of fiber optic cable instead of digging trenches to bury new cables, which is a more expensive process. To multiplex the data, the network separates the cable into channels. The data transmission speed is comparable to Gigabit <a href="https://www.techtarget.com/searchnetworking/definition/Ethernet">Ethernet</a> speeds.</p> <section class="section main-article-chapter" data-menu-title="SONET components"> <h2 class="section-title"><i class="icon" data-icon="1"></i>SONET components</h2> <p>The network elements defined in SONET include the following:</p> <ul class="default-list"> <li><b>Synchronous Transport Signal multiplexer and demultiplexer.</b> The STS multiplexer multiplexes signals and converts electrical signals to optical ones. The demultiplexer reverses this process, condensing signals and converting optical signals back to electrical ones.</li> <li><b>Regenerator.</b> The regenerator increases incoming optical signals, which enables them to travel farther.</li> <li><b>Add-drop multiplexer.</b> The ADM adds or removes signals from sources.</li> </ul> <p>SONET connections break down among sections, lines and paths. Sections connect two devices, while lines connect two multiplexers. Paths connect networks from end to end.</p> <p>SONET also defines the following four layers:</p> <ol class="default-list"> <li><b>Path layer.</b> Moves signals from sources to destinations.</li> <li><b>Line layer.</b> Moves across cables.</li> <li><b>Section layer.</b> Defines the movement of signals across cables.</li> <li><b>Photonic layer.</b> Specifies optical fiber channels.</li> </ol> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/fiber_optic_cable.jpg"> <img data-src="https://www.techtarget.com/rms/onlineImages/fiber_optic_cable_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/fiber_optic_cable_mobile.jpg 960w,https://www.techtarget.com/rms/onlineImages/fiber_optic_cable.jpg 1280w" alt="Diagram of fiber optic cable." height="290" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>SONET transmits data streams across a fiber optic cable. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="SONET standards"> <h2 class="section-title"><i class="icon" data-icon="1"></i>SONET standards</h2> <p>ANSI T1.105 and T1.117 specify SONET standards. SONET provides standards for line rates up to a maximum of 10 gigabits per second (Gbps). Actual line rates can approach 30 Gbps.</p> <p>SONET's basic unit is optical carrier level 1 (OC-1), which supports up to 51.84 megabits per second. OC-3 -- the next level up -- supports up to triple the <a href="https://www.techtarget.com/searchnetworking/definition/bandwidth">bandwidth</a>. Each optical carrier level increases by multiples of four, e.g., OC-3, OC-12 and OC-48, all the way up to OC-768. OC-24 is the only exception.</p> </section> <section class="section main-article-chapter" data-menu-title="SONET benefits"> <h2 class="section-title"><i class="icon" data-icon="1"></i>SONET benefits</h2> <p>SONET has several benefits, including the following:</p> <ul class="default-list"> <li>High data rates, up to 40 Gbps at OC-768.</li> <li>Large transmit distances.</li> <li>Multiple data types, such as data, voice and video.</li> <li>High-level protocols, such as <a href="https://www.techtarget.com/searchunifiedcommunications/definition/Internet-Protocol">Ineternet Protocol</a>.</li> <li>Interoperable infrastructure that enables organizations to use devices from multiple vendors.</li> </ul> <p>One disadvantage of SONET, however, is its high cost, which could dissuade some organizations from implementing it.</p> </section> <section class="section main-article-chapter" data-menu-title="SONET vs. SDH"> <h2 class="section-title"><i class="icon" data-icon="1"></i>SONET vs. SDH</h2> <p>Synchronous Digital Hierarchy (<a href="https://www.techtarget.com/searchnetworking/definition/SDH">SDH</a>) is the international equivalent of SONET, created by the International Telecommunication Union. SONET and SDH are similar standards used for the same reason, and SDH can work with SONET line rates.</p> <p>However, SDH's basic unit is Synchronous Transport Module level 1 (STM-1) instead of SONET's OC levels. SONET and SDH also have different data restructuring structures. SDH frames comprise 19,440 bits and use STM, while SONET frames comprise 6,480 bits and use STS.</p> </section> Synchronous Optical Network (SONET) is a North American standardized digital communication protocol for synchronous data transmission over optical fibers. https://cdn.ttgtmedia.com/visuals/digdeeper/4.jpg https://www.techtarget.com/searchnetworking/definition/Synchronous-Optical-Network Mon, 18 Aug 2025 09:00:00 GMT What is Synchronous Optical Network (SONET)? <p>Unshielded twisted pair (UTP) is a ubiquitous type of copper cabling used in networking technologies, such as telephone wiring and local area networks (<a href="https://www.techtarget.com/searchnetworking/definition/local-area-network-LAN">LANs</a>). Different uses, such as analog, <a href="https://www.techtarget.com/whatis/definition/digital">digital</a> and <a href="https://www.techtarget.com/searchnetworking/definition/Ethernet">Ethernet</a>, require different pair multiples.</p> <p>Alternatives to UTP cable include <a href="https://www.techtarget.com/searchnetworking/definition/coaxial-cable-illustrated">coaxial</a> and <a href="https://www.techtarget.com/searchnetworking/definition/fiber-optics-optical-fiber">fiber optic</a> cables. Each type of cabling has benefits and tradeoffs, but enterprises typically favor UTP cable due to its low cost and easy installation.</p> <p>Alexander Graham Bell invented the twisted-pair design in 1881.</p> <section class="section main-article-chapter" data-menu-title="How UTP cables work: Twisted pair design"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How UTP cables work: Twisted pair design</h2> <p>Up to four <a href="https://www.techtarget.com/searchdatacenter/definition/twisted-pair">twisted pairs</a> of copper wires are enclosed in a protective plastic cover inside a UTP cable. The greater the number of pairs, the more <a href="https://www.techtarget.com/searchnetworking/definition/bandwidth">bandwidth</a> available. The two individual wires in a single pair twist around each other, followed by each pair twisting around each other as well. This reduces <a href="https://www.techtarget.com/searchnetworking/definition/crosstalk">crosstalk</a> and <a href="https://www.techtarget.com/searchmobilecomputing/definition/electromagnetic-interference">electromagnetic interference</a>, both of which degrade network performance. Each signal on a twisted pair requires both wires.</p> <p>Twisted pairs are color-coded to make it easy to identify each pair. In North America, one wire in a pair is identified by one of five colors: blue, orange, green, brown or gray. Most cables use the first four colors, and the wires are typically solid-colored.</p> <p>The solid-colored wire is paired with a wire from a different color group: white, red, black, yellow or violet. Typically, this second wire is striped with the color of its mate so that they can be easily identified and matched. For example, a solid blue wire would be paired with a white-and-blue striped wire.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/UTP_color.jpg"> <img data-src="https://www.techtarget.com/rms/onlineImages/UTP_color_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/UTP_color_mobile.jpg 960w,https://www.techtarget.com/rms/onlineImages/UTP_color.jpg 1280w" alt="Diagram of unshielded twisted pair (UTP) color coding." height="302" width="519"> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="Types of UTP cables"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Types of UTP cables</h2> <p>The TIA/EIA-568 standard defines the <a href="https://www.techtarget.com/searchdatacenter/definition/Categories-of-twisted-pair-cabling-systems">categories of UTP</a> cables. Each type begins with the prefix CAT -- as in <i>category</i> -- and supports a different amount of bandwidth.</p> <ul class="default-list"> <li><b>CAT3.</b> Rarely used today, CAT3 is usually deployed in phone lines. It supports 10 megabits per second (<a href="https://www.techtarget.com/searchnetworking/definition/Mbps">Mbps</a>) for up to 100 meters.</li> <li><b>CAT4.</b> Typically used in token ring networks, CAT4 supports 16 Mbps for up to 100 meters.</li> <li><b>CAT5.</b> Used in Ethernet-based LANs, CAT5 contains two twisted pairs. It supports 100 Mbps for up to 100 meters.</li> <li><b>CAT5e.</b> Used in Ethernet-based LANs, CAT5e contains four twisted pairs. It supports 1 <a href="https://www.techtarget.com/searchnetworking/definition/gigabit">gigabit</a> per second (Gbps) for 100 meters.</li> <li><b>CAT6.</b> Used in Ethernet-based LANs and data center networks, CAT6 contains four tightly wound twisted pairs. It supports 1 Gbps for up to 100 meters and 10 Gbps for up to 50 meters.</li> <li><b>CAT6a.</b> Used in high-speed Ethernet-based enterprise networks, CAT6a is an augmented version of CAT6. It supports greater bandwidth.</li> </ul> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/UTP_copper.jpg"> <img data-src="https://www.techtarget.com/rms/onlineImages/UTP_copper_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/UTP_copper_mobile.jpg 960w,https://www.techtarget.com/rms/onlineImages/UTP_copper.jpg 1280w" alt="Table of unshielded twisted pair cable categories." height="307" width="519"> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="Shielded vs. unshielded twisted pair cables"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Shielded vs. unshielded twisted pair cables</h2> <p>The word <i>unshielded</i> in UTP refers to the lack of metallic shielding around the copper wires. By its nature, the twisted-pair design <a target="_blank" href="https://emianalyst.wordpress.com/2016/08/31/how-cable-twisting-improves-emi/" rel="noopener">minimizes</a> electromagnetic interference by providing balanced signal transmission, making a physical shield unnecessary.</p> <p>Different twist rates -- the varying number of twists between different pairs -- also reduce crosstalk. These protections come from how the wires are physically laid out, so bending or stretching a UTP cable too much can damage the pairs and make interference more likely to occur.</p> <p>In a shielded twisted pair (<a href="https://www.techtarget.com/searchnetworking/definition/shielded-twisted-pair">STP</a>), a shield encloses the wires and functions as a grounding mechanism to protect people and equipment from the dangers of high voltage and shock. This provides greater protection from electromagnetic and radio frequency interference. However, an STP cable is more expensive and difficult to install than a UTP cable.</p> </section> Unshielded twisted pair (UTP) is a ubiquitous type of copper cabling used in networking technologies, such as telephone wiring and local area networks (LANs). https://cdn.ttgtmedia.com/visuals/digdeeper/3.jpg https://www.techtarget.com/searchnetworking/definition/Unshielded-Twisted-Pair Thu, 31 Jul 2025 12:00:00 GMT What is an unshielded twisted pair (UTP)? <p>Telematics is a term that combines the words <em><a href="https://www.techtarget.com/searchnetworking/definition/telecommunications-telecom">telecommunications</a></em> and <i>informatics</i> to describe the use of communications and IT to transmit, store and receive information from devices to remote objects over a network.</p> <p>Telematics refers to the convergence of telecommunications and information processing. It is primarily used in the automotive industry, but other industries have developed use cases as well.</p> <p>Telematics is the English translation of <i>télématique</i>, a word coined by French authors Simon Nora and Alain Minc in their 1978 report, "L'informatisation de la Societe," which forecast the influence technology would have on society. Given their views, telematics now includes the internet because networks running on Internet Protocol (<a href="https://www.techtarget.com/searchunifiedcommunications/definition/Internet-Protocol">IP</a>) facilitate the transmission of data across countless networks globally connected over multiple telecommunications network backbones.</p> <section class="section main-article-chapter" data-menu-title="How telematics works"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How telematics works</h2> <p>Telematics is a varied field, but it is mostly used in vehicular technologies and road transportation. It uses communications-enabled devices to store, send and receive information that can control remote objects, specifically in moving vehicles using navigation systems. The integration of the Global Positioning System (<a href="https://www.techtarget.com/searchmobilecomputing/definition/Global-Positioning-System">GPS</a>) into mobile devices and computers enables telematics to mark its location and communicate with a wide range of vehicles.</p> <p>Other industries that use telematics include the following:</p> <ul class="default-list"> <li>Telecommunications.</li> <li>Wireless communications.</li> <li>Electrical engineering.</li> <li>Computer science.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Vehicle telematics"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Vehicle telematics</h2> <p>In commercial usage, telematics is usually synonymous with <i>vehicle telematics</i>. The automotive industry uses telematics to describe onboard communications services and applications. Cars, trucks, buses and other vehicles use GPS receivers and telematics devices installed in each vehicle. Technologies that support vehicle telematics include the following:</p> <ul class="default-list"> <li><b>Fleet telematics. </b><i>Fleet telematics</i> refers to the use of telematics to manage and monitor commercial vehicle operations, locations and status. These systems enable information exchange between a central location and individual fleet vehicles. A fleet vehicle can include trucks, ambulances, municipal vehicles and school buses.</li> <li><b>GPS. </b>GPS tracking and other wireless communications transmit information to and from a vehicle's computerized systems. This enables services such as GPS navigation, roadside assistance, remote diagnostics and fleet management. General Motors first popularized automotive telematics with its OnStar system.</li> <li><b>Wireless. </b><a href="https://www.techtarget.com/searchmobilecomputing/definition/Wi-Fi">Wi-Fi</a> and cellular networks -- such as fourth-generation wireless (4G) LTE or <a href="https://www.techtarget.com/searchnetworking/definition/5G">5G</a> -- could also facilitate communication between vehicles and applications or services. Faster wireless networks enable more advanced onboard services, such as vehicle firmware updates, multiuser Wi-Fi hotspots and streaming video for passengers. This eliminates some tasks that previously required a visit to a car dealership.</li> </ul> <p>Combining telematics systems with sensors has opened up additional opportunities in the automotive industry and beyond. For example, telematics systems help shipping companies analyze how much time trucks spend idling. Car insurance companies can offer lower premiums to customers who are safe drivers. Telematics also supports other industries, such as car-sharing. Zipcar, for example, uses onboard network-based services to enable usage-based pricing and self-service reservations.</p> <p>Beyond automotive applications, other industries have developed other telematics use cases, such as monitoring water and air pollution, providing medical and healthcare information, and enabling distance learning.</p> </section> <section class="section main-article-chapter" data-menu-title="Telematics companies"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Telematics companies</h2> <p>Some third-party companies offering customers communications and information management for their fleet vehicles brand themselves as telematics providers or fleet management services providers. These providers often specialize in specific services for their customer bases, including the following:</p> <ul class="default-list"> <li>GPS fleet trackers.</li> <li>GPS tracking software.</li> <li>Vehicle security services.</li> </ul> </section> Telematics is a term that combines the words 'telecommunications' and 'informatics' to describe the use of communications and IT to transmit, store and receive information from devices to remote objects over a network. https://cdn.ttgtmedia.com/visuals/digdeeper/2.jpg https://www.techtarget.com/searchnetworking/definition/telematics Tue, 15 Jul 2025 09:00:00 GMT What is telematics? <p>The domain name system (DNS) is a naming database in which internet <a href="https://www.techtarget.com/whatis/definition/domain">domain</a> names are located and translated into <a href="https://www.techtarget.com/whatis/definition/IP-address-Internet-Protocol-Address">Internet Protocol (IP) addresses</a>. The DNS maps the name people use to locate a website to the IP address that a computer uses to locate that website.</p> <p>For example, if someone types <i>example.com</i> into a web browser, a server behind the scenes maps that name to the corresponding IP address 203.0.113.72, which is reserved for use in documentation and examples.</p> <p>IP addresses are composed of four sets of numbers, or octets, that are separated by periods. The first part of the IP address identifies the network ID of the connecting device or service; the second set of numbers represents the subpart or subnet of the network where the connecting device or service is located; the third set of numbers is the IP address of the host ID of the site to which the requestor wishes to connect; and the last two octets define the specific host that is used for communicating with the requestor.</p> <p>Web browsing and most other internet activities rely on DNS to quickly provide the information necessary to connect users to remote hosts. DNS mapping is distributed throughout the internet in a hierarchy of authority. Internet service providers (<a href="https://www.techtarget.com/whatis/definition/access-provider">ISPs</a>), enterprises, governments, universities and other organizations typically have their own assigned ranges of IP addresses and an assigned domain name. They also usually run DNS servers to manage mapping those names to those addresses.</p> <section class="section main-article-chapter" data-menu-title="DNS naming structure"> <h2 class="section-title"><i class="icon" data-icon="1"></i>DNS naming structure</h2> <p>DNS servers direct internet traffic by referencing the domain names of sites that users request. The domain name is usually contained in a URL. It is made of multiple parts called <i>labels</i>. The domain hierarchy is read from right to left, with each section denoting a subdivision.</p> <p>The top-level domain (TLD) appears after the period in the domain name. Examples of TLDs include .com, .org and .edu, but there are many others. Some TLDs denote a country code or geographic location, such as .us for the United States or .ca for Canada.</p> <p>Each label on the left-hand side of the TLD denotes another subdomain of the domain to the right. For example, in the URL www.techtarget.com, <i>techtarget</i> is a subdomain of .com, and <i>www</i> is a subdomain of techtarget.com.</p> <p>There can be up to 127 levels of subdomains, and each subdomain label can have up to 63 characters. The total domain name can be up to 253 characters. Other rules include not starting or ending labels with hyphens and not having a fully numeric TLD name.</p> <p>In 1987, the Internet Engineering Task Force (<a href="https://www.techtarget.com/whatis/definition/IETF-Internet-Engineering-Task-Force">IETF</a>) specified <a href="https://datatracker.ietf.org/doc/html/rfc1035" target="_blank" rel="noopener">rules</a> about implementing domain names in Request for Comments (RFC) 1035.</p> </section> <section class="section main-article-chapter" data-menu-title="Why is DNS important?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Why is DNS important?</h2> <p>Internet operations depend on DNS, which functions like a virtual phone book and is the mapping apparatus that enables users and resources to identify and connect with each other. Internet traffic flows are highly dependent on DNS behind-the-scenes mapping that can automatically connect and direct internet traffic from point to point. Without DNS automatic mapping facilities, internet users and service requesters would have to know and manually enter the IP addresses of the services and sites to which they wish to connect. Additionally, DNS servers apply security verifications that can prevent security attacks and attempts.</p> <div class="youtube-iframe-container"> <iframe id="ytplayer-0" src="https://www.youtube.com/embed/9d0iu2Q6iMU?autoplay=0&modestbranding=1&rel=0&widget_referrer=null&enablejsapi=1&origin=https://www.techtarget.com" type="text/html" height="360" width="640" frameborder="0"></iframe> </div> </section> <section class="section main-article-chapter" data-menu-title="How DNS works"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How DNS works</h2> <p>DNS servers convert URLs and domain names into IP addresses that computers can understand and use. They translate what a user types into a browser into something the machine can use to find a webpage. This process of translation and lookup is called <i>DNS resolution</i>. Its purpose is to translate a human language-based name, like <i>techtarget.com</i>, into a numerical IP address that <a href="https://www.techtarget.com/searchnetworking/definition/TCP-IP">TCP/IP</a> requires to locate a website or other internet resource.</p> <p>There are two types of DNS resolution techniques:</p> <ol class="default-list"> <li><b>Recursive resolution.</b> In DNS recursive resolution, the human-readable domain name is translated into a numbered IP address by recursive resolvers. The user workstation, device or IT service sends the human-readable domain name identifier of the requested internet resource to the local network DNS server, which consults its database to find the associated IP address for that identifier. The DNS server uses the IP address to go out to the internet and retrieve the requested website or resource.</li> <li><b>Iterative resolution.</b> In the case of iterative resolution, the initial request that the user workstation, device or IT service sends to its local network DNS server is unsuccessful, likely because the internet resource being requested is on a different network that is governed by its own DNS server. In this case, the initial request is iteratively sent to several different DNS servers on different networks until the DNS server that contains the cross-reference and IP address translation for the requested internet resource is found. The IP address is then used to retrieve the requested resource for the requester.</li> </ol> <p>The basic process of DNS resolution follows these steps:</p> <ol class="default-list"> <li>The user enters a web address or domain name into a browser.</li> <li>The browser sends a recursive DNS query message to the network to determine to which IP address or network the domain corresponds.</li> <li>The query goes to a recursive DNS server, which is usually managed by the ISP. If the recursive resolver has the address, it returns it to the user, and the webpage loads.</li> <li>If the recursive DNS server has no answer, it queries a series of other servers in the following order: DNS root name servers, TLD name servers and authoritative name servers.</li> <li>The three server types work together and continue redirecting until they retrieve a DNS record that contains the queried IP address. They send this information to the recursive DNS server, and the webpage the user is looking for loads. DNS root name servers and TLD servers primarily redirect queries and rarely provide the resolution themselves.</li> <li>The recursive server stores, or <a href="https://www.techtarget.com/searchstorage/definition/cache">caches</a>, the IP address for the domain name. The next time it receives a request for that domain name, it can respond directly to the user instead of querying other servers.</li> <li>If the query reaches the authoritative server and it cannot find the information, it returns an error message.</li> </ol> <p>The entire process of querying the various servers takes a fraction of a second and is usually imperceptible to the user.</p> <p>DNS servers answer questions from both inside and outside their domains. When a server receives a request from outside the domain for information about a name or address inside the domain, it provides an authoritative answer.</p> <p>When a server gets a request from within its domain for a name or address outside that domain, it forwards the request to another server, usually one managed by its ISP.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/networking-how_dns_works-f.png"> <img data-src="https://www.techtarget.com/rms/onlineImages/networking-how_dns_works-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/networking-how_dns_works-f_mobile.png 960w,https://www.techtarget.com/rms/onlineImages/networking-how_dns_works-f.png 1280w" alt="An image showing the five steps in the DNS process." height="246" width="559"> <figcaption> <i class="icon pictures" data-icon="z"></i>DNS servers talk to each other to answer a query from a client. They cache the necessary information and relay it back to the client so they can get online. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="DNS server types"> <h2 class="section-title"><i class="icon" data-icon="1"></i>DNS server types</h2> <p>DNS uses different servers to locate the IP addresses of the domain names that users request. The following is a breakdown of how these various DNS servers work together:</p> <ol class="default-list"> <li><b>Recursive server. </b>This DNS server is within the same network as the user, so it is the first DNS server that attempts translation of the domain name submitted by the user into an IP address. The user enters <i>www.getthis.com</i>. The request goes out to the recursive server, which searches its cross-reference database of domain names and IP addresses. Unfortunately, the recursive server that is on the user's network cannot find the IP address domain name <i>www.getthis.com</i>.</li> <li><b>Root name server. </b>The recursive server on the user's network then reaches out to the root name server, which is a master index of all the servers with the information being queried. The Internet Corporation for Assigned Names and Numbers, or <a href="https://www.techtarget.com/whatis/definition/ICANN-Internet-Corporation-for-Assigned-Names-and-Numbers">ICANN</a>, oversees these servers. The root server looks at the TLD of the resource being requested -- for example, .com, .org or .edu.</li> <li><b>TLD server.</b> Based on the TLD name of the resource requested, the root server calls the correct TLD server. For example, <i>www.getthis.com</i> has .com as its TLD name, so the root server routes the user's request to the TLD server that contains an IP number cross-reference database for all .com domains.</li> <li><b>Authoritative server. </b>The authoritative server is the final authority for all internet assets, as it holds the DNS records for the sites and resources that users access. The authoritative server works with recursive servers, root servers and TLD servers to return the full resource or website requested by the user. In the <i>www.getthis.com</i> example, the resource request was first routed to a recursive server, which could not find the website. It was then forwarded to the root server, which contained a master index of DNS names, and then directed the request to a .com domain TLD server. The .com TLD server found the <i>www.getthis.com</i> domain name and its corresponding IP address and then contacted the authoritative server, which contained the domain itself. It was able to fulfill the user request by facilitating the complete delivery of the requested domain content to the user.</li> </ol> </section> <section class="section main-article-chapter" data-menu-title="Types of DNS queries"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Types of DNS queries</h2> <p>Recursive and iterative queries are the two types of queries most often executed when users or IT services request internet resources from DNS. However, the following other types of DNS queries can also occur:</p> <ul class="default-list"> <li><b>Nonrecursive queries. </b>These are queries for which the recursive resolver server already knows where to get the answer. The answer is either cached on the recursive server itself, or the recursive server knows to skip the root and TLD servers and go directly to a specific authoritative server. The query is nonrecursive because there is no need -- and, therefore, no request -- for any more queries. Nonrecursive queries resolve in the answer. If a recursive resolver has cached an IP address from a previous session and serves that address upon the next request, that is considered a nonrecursive query.</li> <li><b>Records not found queries. </b>These are cases where the recursive, root level, TLD and authoritative servers have worked together to locate a website or resource requested, but they cannot find it. It is possible that a user might have mistyped a domain name, or the domain name requested does not exist. In these cases, a <i>not found</i> error message is returned to the user.</li> <li><b>DNS not responding queries. </b>These queries occur<b> </b>when DNS servers are either down or cannot be reached. Sometimes, this is a systemic problem that users or IT cannot directly fix, but other times, it is possible to get DNS working again by either trying to access the internet resource requested through an alternate web browser or by rebooting a local router.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Common DNS records"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Common DNS records</h2> <p>DNS records are the information a query seeks. Depending on the query, client or application, different information is required. There are many DNS record types, each with its own purpose in denoting how a query should be treated. The following are common DNS records:</p> <ul class="default-list"> <li><b>A </b><b>or AAAA </b><b>record.</b> This stands for <i>address</i> and holds the IP address of a domain. These records only apply to IP addresses that are registered on IP version 4 (IPv4), which most companies are still running. The issue with IPv4 is that it has a finite number of IP addresses that can run on it, but <a href="https://www.techtarget.com/searchnetworking/tip/How-enterprises-can-migrate-from-IPv4-to-IPv6">its eventual replacement, IPv6</a>, has the potential to carry limitless IP addresses with stronger security. On IPv6, the address record known as the A record on IPv4 is called the AAAA record and uses the longer IP address format of IPv6 addresses. Most websites only have one A or AAAA record, but some larger sites have several. This helps with load balancing because different A or AAAA records can be used for different users in heavy traffic.</li> <li><b>Name server </b><b>record.</b><b> </b>The DNS name server record denotes which authoritative DNS server is responsible for having all the information about a given domain so users can be routed to the website or resource they are requesting. Given the importance of the DNS authoritative name server, it is not uncommon for domains to use both primary and backup name servers to increase reliability. Multiple name server records are created to enable queries to be routed to different DNS authoritative name servers.</li> <li><b>TXT record.</b><b> </b>TXT records enable administrators to enter text into DNS. The original purpose was to put human-readable notes in DNS, but today, machine-readable notes are often put there. TXT records are used to confirm domain ownership, secure email and prevent email spam.</li> <li><b>Canonical name record. </b><a href="https://www.techtarget.com/searchwindowsserver/definition/canonical-name">CNAME</a> records are used to resolve situations where there might be multiple domain names or aliases for a particular website or internet resource. A CNAME search expands the DNS search to alternate domain names besides the original name the user entered or what was loaded into the A or AAAA record. By using the CNAME records to try out alternative alias names for a requested website or resource, DNS servers enhance their chances of locating the correct name of the website or resource originally requested. An example is if a user keyed in a URL of <i>searchsecurity.techtarget.com</i>. In the event the DNS server could not locate this name and its corresponding IP address for routing, the server queries the CNAME aliases, such as <i>techtarget.com</i>.</li> </ul> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/cname_dns_record_request_sequence-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/cname_dns_record_request_sequence-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/cname_dns_record_request_sequence-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/cname_dns_record_request_sequence-f.png 1280w" alt="A diagram showing the CNAME DNS record request process." height="235" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>CNAME records are used as an alias for domain names that share one IP address. In this case, 'Searchsecurity.techtarget.com' is an alias for 'Techtarget.com;' they both point to the same IP address. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="How does DNS increase web performance?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How does DNS increase web performance?</h2> <p>Servers can cache the A or AAAA records or IP addresses they receive from DNS queries for a set time. Caching promotes efficiency, enabling servers to respond quickly the next time a request for the same IP address comes in.</p> <p>For example, if everyone in an office needs to access the same training video on a particular website on the same day, the local DNS server only has to resolve the name once, and then it can serve all the other requests out of its cache. The length of time the record is held -- also known as the <i>time to live</i> (<a href="https://www.techtarget.com/searchnetworking/definition/time-to-live">TTL</a>) -- is set by administrators and depends on various factors. Longer time periods decrease the load on servers, and shorter ones ensure the most accurate responses.</p> </section> <section class="section main-article-chapter" data-menu-title="DNS caching"> <h2 class="section-title"><i class="icon" data-icon="1"></i>DNS caching</h2> <p>DNS caching aims to reduce the time it takes to get an answer to a DNS query. Caching enables DNS to store previous answers to queries closer to clients and get that information to them faster the next time it is queried.</p> <p>DNS data can be cached in the following places:</p> <ul class="default-list"> <li><b>Browser.</b> Most browsers, like Apple Safari, Google Chrome and Mozilla Firefox, cache DNS data by default for a set amount of time. The browser is the first cache that gets checked when a DNS request is made -- before the request leaves the machine for a local DNS resolver server.</li> <li><b>Operating system.</b> Many OSes have built-in DNS resolvers called <i>stub resolvers</i> that cache DNS data and handle queries before sending them to an external server. The OS is usually queried after the browser or other querying application.</li> <li><b>Recursive resolver. </b>The answer to a DNS query can also be cached on the DNS recursive resolver. Resolvers might have some of the records necessary to return a response and be able to skip some steps in the DNS resolution process. For example, if the resolver has A or AAAA records but not the corresponding name server records, it can skip the root server and query the TLD server directly.</li> </ul> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/dns_caching_flow-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/dns_caching_flow-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/dns_caching_flow-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/dns_caching_flow-f.png 1280w" alt="A diagram showing how DNS queries flow from the client computer to the internet service provider." height="230" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>DNS queries look for the records in local caches, both on the DNS resolver within the operating system and on local applications, before queries are sent to external recursive servers. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="DNS security"> <h2 class="section-title"><i class="icon" data-icon="1"></i>DNS security</h2> <p>Several DNS vulnerabilities have been discovered over time. One such vulnerability is DNS <a href="https://www.techtarget.com/searchsecurity/definition/cache-poisoning">cache poisoning</a>. This type of cyberattack distributes data to caching resolvers, posing as an authoritative origin server. The data can then present false information and affect TTL. Application requests can also be redirected to a malicious host network.</p> <p>An individual with malicious intent can create a dangerous website with a misleading title and try to convince users that the website is real, giving them access to the user's information. By replacing a character in a domain name with a similar-looking character -- such as replacing the number 1 with the letter l, which looks similar -- a user could be fooled into selecting a false link. This is commonly exploited with <a href="https://www.techtarget.com/searchsecurity/definition/phishing">phishing</a> attacks.</p> <p>Individuals can use DNS Security Extensions to enhance security. This suite of extensions supports <a href="https://www.techtarget.com/searchsecurity/definition/cryptography">cryptographically</a> signed responses by ensuring the authenticity of DNS data.</p> </section> <section class="section main-article-chapter" data-menu-title="Brief history of DNS"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Brief history of DNS</h2> <p>In the 1970s, all hostnames and their corresponding numerical addresses were contained in a file called hosts.txt that was maintained by Elizabeth Feinler from the Stanford Research Institute. This was known as the Advanced Research Projects Agency Network, or <a href="https://www.techtarget.com/searchnetworking/definition/ARPANET">ARPANET</a>, directory, and Feinler manually assigned numerical addresses to domain names. Adding a new name to the directory required a phone call to her.</p> <p>By the 1980s, this system had become too inefficient to maintain. In 1983, DNS was created to distribute what was initially one centralized file with every address in it across multiple servers and locations.</p> <p>In 1986, IETF listed DNS as one of the original internet standards. It published two documents -- RFC 1034 and RFC 1035 – describing the DNS protocol and outlining the types of data it could carry.</p> <p>Since then, DNS has been consistently updated and expanded to accommodate the increasingly complex internet. Today, companies such as Amazon Web Services, Cloudflare, Google, Microsoft and Rackspace offer their own DNS hosting services.</p> <p><em>Explore <a href="https://www.techtarget.com/searchnetworking/feature/12-common-network-protocols-and-their-functions-explained">common network protocols</a>, and learn their main functions and importance. </em></p> </section> The domain name system (DNS) is a naming database in which internet domain names are located and translated into Internet Protocol (IP) addresses. https://cdn.ttgtmedia.com/visuals/digdeeper/5.jpg https://www.techtarget.com/searchnetworking/definition/domain-name-system Tue, 08 Jul 2025 09:00:00 GMT What is the domain name system (DNS)? <p>Attenuation is a general term referring to when any type of signal -- digital or analog -- reduces in strength. Sometimes called <i>loss</i>, attenuation is a natural consequence of signal transmission over long distances.</p> <p>Attenuation is important in <a href="https://www.techtarget.com/searchnetworking/definition/telecommunications-telecom">telecommunications</a> and ultrasound applications. It's critical to determining signal strength as a function of distance. Minimizing the loss of attenuation is important in microwave, wireless and cellular applications because an optical data link depends on modulated light reaching the receiver with enough power to be correctly demodulated. Attenuation reduces this power, resulting in a loss of the transmitted light signal.</p> <p>In conventional and <a href="https://www.techtarget.com/searchnetworking/definition/fiber-optics-optical-fiber">fiber optic</a> cables, specify attenuation by the number of decibels (dB) per foot, 1,000 feet, kilometer or mile. The less attenuation per unit of distance, the more efficient a cable is.</p> <section class="section main-article-chapter" data-menu-title="Attenuation in networking"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Attenuation in networking</h2> <p>In computer networking, attenuation is the loss of communication signal strength measured in decibels. As the attenuation rate increases, the transmission, such as a phone call or an email a user tries to send, becomes more distorted.</p> <p>Attenuation occurs on computer networks because of the following factors:</p> <ul class="default-list"> <li><b>Range</b><b>.</b> Both wired and wireless transmissions gradually dissipate in strength over longer distances.</li> <li><b>Interference</b><b>.</b> Radio <a href="https://www.techtarget.com/searchmobilecomputing/definition/electromagnetic-interference">interference</a>, weather or physical obstructions, such as walls, dampen communication signals on wireless networks.</li> <li><b>Wire type and size</b><b>.</b> Thinner wires suffer from more attenuation than thicker wires on wired networks.</li> </ul> <p>Line attenuation on a Digital Subscriber Line network measures signal loss between a DSL provider's access point and an endpoint. Attenuation is critical on DSL networks. When line attenuation values are too large, it might restrict available data rates. Line attenuation values on a DSL connection are typically between 5 dB and 50 dB. The lower the values, the stronger the signals.</p> <p>Wi-Fi supports dynamic rate scaling, which enhances the distance at which wireless devices can connect to each other in exchange for lower network performance at longer distances. Depending on the line's transmission quality, dynamic rate scaling automatically regulates the connection's maximum data rate up or down in fixed increments.</p> </section> <section class="section main-article-chapter" data-menu-title="How to measure attenuation"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How to measure attenuation</h2> <p>The extent of attenuation is usually expressed in decibels but can also be expressed in voltage.</p> <h3>Attenuation in decibels</h3> <p>P<sub>s</sub> is the signal power at the transmitting end (source) of a communications circuit, and P<sub>d</sub> is the signal power at the receiving end (destination). In this paradigm, P<sub>s</sub> > P<sub>d</sub>. Use the following formula to determine the power attenuation -- A<sub>p</sub> -- in decibels.</p> <p style="text-align: center;">A<sub>p</sub> = 10 log<sub>10</sub>(P<sub>s</sub>/P<sub>d</sub>)</p> <h3>Attenuation in voltage</h3> <p>In this equation, A<sub>v</sub> is the voltage attenuation in decibels. V<sub>s</sub> is the source signal voltage, and V<sub>d</sub> is the destination signal voltage. Use the following formula to determine A<sub>v</sub>.</p> <p style="text-align: center;">A<sub>v</sub> = 20 log<sub>10</sub>(V<sub>s</sub>/V<sub>d</sub>)</p> </section> <section class="section main-article-chapter" data-menu-title="How to increase signal strength to prevent attenuation"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How to increase signal strength to prevent attenuation</h2> <p><a href="https://www.techtarget.com/whatis/definition/amplifier">Amplification</a> is a technique to increase signal strength to prevent attenuation. Signal amplification electrically increases a line signal's strength by one of several methods. On computer networks, amplification typically includes logic for noise reduction to prevent the underlying message data from becoming corrupted.</p> <p>A <a href="https://www.techtarget.com/searchnetworking/tip/An-introduction-to-8-types-of-network-devices">network repeater device</a> integrates a signal amplifier into its circuitry. Repeaters act as an intermediary between two message endpoints and boost signal strength to overcome attenuation. This is helpful for transmitting long-distance signals via cable. This greatly increases the maximum communication range.</p> <p>The repeater performs the following tasks:</p> <ul class="default-list"> <li>Receives data from the original sender or another upstream repeater.</li> <li>Processes data through the amplifier.</li> <li>Transmits the stronger signal forward to its ultimate destination.</li> </ul> <p>In addition to repeaters, directional antennas and other antenna upgrades also work well to boost signals.</p> </section> <section class="section main-article-chapter" data-menu-title="Attenuation in other contexts"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Attenuation in other contexts</h2> <p><i>Attenuation</i> is also used in contexts other than computer networking. Sound mixers and audiophiles use attenuation techniques to manage sound levels when blending different audio recordings.</p> <p>Attenuation is also frequently used in the radiology field to discuss the characteristics of an anatomical structure represented in an X-ray.</p> <p>In brewing, attenuation refers to the process of converting sugars into alcohol and carbon dioxide by fermentation. The greater the attenuation, the more sugar converts into alcohol. If a beer is more attenuated, then it is drier and more alcoholic than a beer that is less attenuated.</p> </section> Attenuation is a general term referring to when any type of signal -- digital or analog -- reduces in strength. https://cdn.ttgtmedia.com/visuals/digdeeper/5.jpg https://www.techtarget.com/searchnetworking/definition/attenuation Tue, 08 Jul 2025 09:00:00 GMT What is attenuation? <p>A coaxial cable -- or <i>coax cable </i>-- is a type of copper cable specially built with a metal shield and other components engineered to block signal interference.</p> <p>Cable TV companies primarily use coaxial cables to connect their satellite antenna facilities to customers' homes and businesses. Telephone companies sometimes use coax cables to connect central offices to telephone poles near customers. <a href="https://www.techtarget.com/searchdatacenter/definition/Categories-of-twisted-pair-cabling-systems">Twisted pair cabling</a> has largely supplanted coax's widespread use as an <a href="https://www.techtarget.com/searchnetworking/definition/Ethernet">Ethernet</a> connectivity medium in enterprises and data centers.</p> <p>The term <i>coaxial cable</i> derives from its design -- it includes one physical channel that carries the signal surrounded by another concentric physical channel, both running along the same axis. The innermost channel is typically a copper wire surrounded by a layer of insulation between it and the outer channel. The outer channel serves as a ground, typically as copper mesh. Another layer of insulation surrounds both the inner and outer channels. Many of these cables or pairs of coaxial tubes can have a single outer sheathing and, with repeaters, can carry information for a great distance.</p> <p>English engineer and mathematician Oliver Heaviside invented the coaxial cable in 1880. AT&T established its first cross-continental coaxial transmission system in 1940. Depending on the carrier technology -- and other factors -- twisted pair copper wire and <a href="https://www.techtarget.com/searchnetworking/definition/fiber-optics-optical-fiber">optical fiber</a> are alternatives to the coaxial cable.</p> <section class="section main-article-chapter" data-menu-title="How coaxial cables work"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How coaxial cables work</h2> <p>Coaxial cables have concentric layers of electrical conductors and insulating material. This construction ensures signals are enclosed within the cable and prevents signal interference from electrical noise.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_01.jpg"> <img data-src="https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_01_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_01_mobile.jpg 960w,https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_01.jpg 1280w" alt="Diagram of a coaxial cable." height="294" width="520"> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>The concentric layers of coaxial cables are as follows:</p> <ol class="default-list"> <li>The center conductor layer is either a solid or braided, thin copper conducting wire.</li> <li>A dielectric layer made of an insulating material with well-defined electrical characteristics surrounds the wire.</li> <li>A shield layer surrounds the dielectric layer with metal foil or braided copper mesh.</li> <li>An insulating jacket wraps the whole assembly. The coaxial cable's outer metal shield layer is typically grounded in the connectors at both ends. This shields the signals and provides a place for stray interference signals to dissipate.</li> </ol> <p>Coaxial cable design depends on the cable dimensions and materials. Controlling these factors helps create a fixed value for the characteristic <a href="https://www.techtarget.com/whatis/definition/impedance">impedance</a> of a coax cable. Impedance is sensitive to signal frequency. High-frequency signals are partially reflected at impedance mismatches, causing errors. Above 1 GHz, the cable maker must use a dielectric that doesn't attenuate the signal too much or change the characteristic impedance in a way that creates signal reflections.</p> <p>Electrical characteristics of coax are application-dependent and crucial for good performance. Two standard characteristic impedances are the following:</p> <ul class="default-list"> <li>50 ohms, used in moderate power environments.</li> <li>75 ohms, common for connections to antennas and residential installations.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Types of coaxial cables"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Types of coaxial cables</h2> <p>There are numerous types of coaxial cables, some of which include the following:</p> <ul class="default-list"> <li><b>Hard-line coaxial cables.</b> Rely on round copper tubing and a combination of metals as a shield, such as aluminum or copper. These cables are commonly used to connect a transmitter to an antenna.</li> <li><b>Triaxial cables.</b> Have a third, grounded layer of shielding to protect signals transmitted down the cable.</li> <li><b>Rigid-line coaxial cables.</b> Consist of twin copper tubes that function as unbendable pipes. These lines are designed for indoor use between high-power radio frequency (<a href="https://www.techtarget.com/searchnetworking/definition/radio-frequency">RF</a>) transmitters.</li> <li><b>Radiating cable.</b> Mimics many components of the hardline cable. However, it has tuned slots in the shielding matched to the RF wavelength at which the cable operates. It is commonly used in elevators, military equipment and underground tunnels.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Types of connectors"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Types of connectors</h2> <p>Coaxial cables have many different types of connectors separated by two styles: plug and socket connectors. Connector types include the following:</p> <ul class="default-list"> <li><b>Bayonet Neill-Concelman.</b> BNC connectors work with television, video signal and radio below a 4 GHz frequency.</li> <li><b>Threaded Neill-Concelman.</b> TNC connectors are a threaded version of the BNC connector, used in cellphones. TNC connectors operate up to 12 GHz.</li> <li><b>SubMiniature version A.</b> SMA connectors are used with cellphones, Wi-Fi antenna systems, microwave systems and radios. SMA connectors usually operate up to 18 GHz, but some can go up to 26.5 GHz.</li> <li><b>SubMiniature version B.</b> Telecommunications hardware uses SMBs.</li> <li><b>Quick Lock SMA.</b> QMA connectors are a quick-locking variant of SMA connectors used with industrial and communications hardware.</li> <li><b>Radio Corporation of America.</b> Audio and video use RCA connectors. RCA connectors are the grouped yellow, white and red cables used with older televisions. They are also called <i>A/V jacks</i>.</li> <li><b>F connectors.</b> Also called <i>F-type</i> connectors, these are used by digital and cable televisions. These commonly use RG-6 or RG-59 cables.</li> </ul> <p>Coax connectors range from simple single connectors used on cable TV systems to complicated combinations of multiple thin coax links mixed with power and other signal connections and housed in semicustom bodies. These are commonly found in military electronics and avionics.</p> </section> <section class="section main-article-chapter" data-menu-title="Uses of coaxial cables"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Uses of coaxial cables</h2> <p>Homes and small offices use short coaxial cables for cable television, home video equipment, amateur radio equipment and measuring devices. Coaxial cables are also used in automobiles, aircraft, military and medical equipment. Their primary function is to connect satellite dishes, radio and television antennae to their respective receivers.</p> <p>Historically, coaxial cables were also used as an early form of Ethernet, supporting speeds of up to 10 Mbps. Since then, twisted-pair cabling has supplanted the use of coax. However, coax cables remain in use for cable broadband internet.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_02.jpg"> <img data-src="https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_02_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_02_mobile.jpg 960w,https://www.techtarget.com/rms/onlineImages/networking-coaixal_cable_02.jpg 1280w" alt="Table showing common types of coax cables." height="153" width="520"> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="Coax standards"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Coax standards</h2> <p>Nearly 50 distinct standards exist for coaxial cable. They are often designed for specific use cases in amateur radio or low-loss cable television. Because of widespread use in the cable television industry, RG-6 cables with double or quad shields and impedance of 75 ohms are a de facto standard for many industries. Other common coaxial specifications have an impedance of 50, 52 or 93 ohms.</p> <p>Some other examples of coax standards include the following.</p> <ul class="default-list"> <li>RG-59/U, used for carrying broadband signal from closed-circuit TV systems.</li> <li>RG-214/U, used for high-frequency signal transmission.</li> </ul> <p>Mechanical stiffness can vary tremendously, depending on the internal construction and intended use. For example, high-power cables are often made with thick insulation and are very stiff.</p> <p>Some cables are deliberately made with thick center wires. This results in skin-effect resistance from high-frequency signals traveling on, not throughout, the surface of the conductor. A larger center conductor creates a stiff cable with low loss per meter.</p> </section> <section class="section main-article-chapter" data-menu-title="Interference issues with coax"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Interference issues with coax</h2> <p>Coaxial cables can experience various forms of interference. Signal leakage occurs when the electromagnetic field passes through the shielding on the outside of the cable. Other times, an outside signal can leak through the insulation.</p> <p>Straight-line feeds to commercial radio broadcast towers have the least leakage and interference. This is because these cables have smooth, conductive shields with few gaps in them. Interference is most significant in nuclear reactors, which need special shielding.</p> </section> <section class="section main-article-chapter" data-menu-title="Difference between RG-59 and RG-6"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Difference between RG-59 and RG-6</h2> <p>RG-59 and RG-6 cables are commonly used in satellite television and cable modems. Older installations used the RG-59 cable before the implementation of the RG-6 cable. The RG-59 cable is thinner at a 20 American Wire Gauge (<a href="https://www.techtarget.com/searchnetworking/definition/American-Wire-Gauge">AWG</a>) and has a copper center conductor. This cable is better for CCTV and analog video systems, so finding it in older buildings is more likely.</p> <p>The RG-6 cable is a larger 18 AWG cable and has a copper center conductor. The RG-6 cable is frequently paired with high-bandwidth and high-frequency hardware, so internet and satellite signals can run at a higher frequency than traditional analog video.</p> <p>Which cable an individual might need largely depends on the frequency. For requirements above 50 MHz, an individual should use an RG-6 cable.</p> </section> A coaxial cable -- or coax cable -- is a type of copper cable specially built with a metal shield and other components engineered to block signal interference. https://cdn.ttgtmedia.com/visuals/digdeeper/1.jpg https://www.techtarget.com/searchnetworking/definition/coaxial-cable-illustrated Tue, 08 Jul 2025 00:00:00 GMT What is a coaxial cable? <p>Green networking is the practice of selecting energy-efficient networking technologies and products to minimize resource use whenever possible.</p> <p>Although investing in green networking might require an initial cash outlay, the products, services and practices involved typically save money over time.</p> <p>Green networking practices include the following:</p> <ul class="default-list"> <li>Updating IT policies to support the use of green technologies and resources.</li> <li>Increasing the use of off-premises networking, such as cloud services.</li> <li>Updating office space and data centers to be more energy-efficient, such as implementing network <a href="https://www.techtarget.com/searchitoperations/definition/virtualization">virtualization</a> and practicing server consolidation.</li> <li>Upgrading older equipment for newer, more energy-efficient products.</li> <li>Employing <a href="https://www.techtarget.com/searchitoperations/definition/systems-management">systems management</a> to increase efficiency.</li> <li>Substituting remote working, remote administration and video conferencing for travel.</li> <li>Organizing periodic reviews by environmental experts to validate green activities.</li> </ul> <div class="youtube-iframe-container"> <iframe id="ytplayer-0" src="https://www.youtube.com/embed/yGkfBo2iSiI?autoplay=0&modestbranding=1&rel=0&widget_referrer=null&enablejsapi=1&origin=https://www.techtarget.com" type="text/html" height="360" width="640" frameborder="0"></iframe> </div> <section class="section main-article-chapter" data-menu-title="What is the goal of green networks?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>What is the goal of green networks?</h2> <p>A <a href="https://www.techtarget.com/searchdatacenter/tip/How-much-energy-do-data-centers-consume">green data center</a> typically houses the nerve center of a company's networking infrastructure. It stores, manages and disseminates network data. The physical components of the building structure -- environmental and security systems, lighting, electrical and computing resources -- are selected and deployed to minimize the environmental effect, while maximizing energy efficiency.</p> <p>Green data centers, which also house network operations centers (<a href="https://www.techtarget.com/searchnetworking/definition/network-operations-center">NOCs</a>), use the following technologies and strategies:</p> <ul class="default-list"> <li>Redesigned footprints that take up less space.</li> <li>Catalytic converters on backup generators.</li> <li>Low-emission building materials, carpets and paints.</li> <li>Energy-efficient entry points, exit points and window glass.</li> <li>Sustainable landscaping.</li> <li>E-waste recycling.</li> <li>Energy-optimized systems, such as solar farms, data center evaporative cooling and heat pumps.</li> <li>Hybrid or electric vehicles.</li> </ul> <p>Building and certifying a green data center or other facility that supports green networking operations can be costly upfront. But, over time, organizations can save on energy, heating and cooling; networking operations; and systems maintenance.</p> <p>For businesses, the goal of green networks is to <a href="https://www.techtarget.com/searchnetworking/tip/How-to-handle-environmental-regulations-and-green-networking">cut energy consumption and emissions</a> to improve air quality and the overall environment. An environmentally clean and friendly organization is also healthy for employees. Local communities also appreciate green networking facilities.</p> <p>Another goal of green networks is to address and assuage environmental groups' concerns. Organizations that use environmentally responsible technologies might also receive governmental financial incentives.</p> </section> <section class="section main-article-chapter" data-menu-title="Green networking approaches"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Green networking approaches</h2> <p>An organization's commitment to green networking is essential for a successful green strategy.</p> <p>At a fundamental level, network infrastructure configuration doesn't need to change in a green network. However, this assumes the existing configuration already provides necessary services, desired data throughput, latency control and security measures to protect the network and its perimeter from cybersecurity threats.</p> <p>The principal approach to green networking is to replace existing network components with energy-efficient units. If the building that houses network elements doesn't change to a more environmentally friendly facility, then the organization can't significantly optimize the network. However, energy-efficient units can replace the following equipment:</p> <ul class="default-list"> <li>Backup power systems.</li> <li>Heating, ventilation and air conditioning systems.</li> <li>Building security systems.</li> <li>Window glass.</li> </ul> <p>Figure 1 depicts a data center with a green NOC that has energy-efficient systems and technologies to improve the building's environmental footprint. Organizations can implement many of these energy improvements as part of a NOC upgrade.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/green_network_operations_center-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/green_network_operations_center-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/green_network_operations_center-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/green_network_operations_center-f.png 1280w" alt="diagram of a green NOC" height="495" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>Figure 1. In this example of a green NOC, several elements achieve energy efficiency. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>The bulk of a network infrastructure is often external to an organization. Organizations should query the carriers providing connectivity to understand their approach to green technology. Observe and validate the carriers' green activities in switching centers and data centers. Reports on energy savings and other environmental metrics should be available for customers to review.</p> <p>Certain metrics demonstrate and certify that buildings are energy-efficient and minimize environmental damage. Green networking centers conform to one or both of two metrics that measure energy usage and sustainability.</p> <ol class="default-list"> <li><b>Power usage effectiveness.</b> Introduced by The Green Grid -- an affiliate member of the Information Technology Industry Council -- in 2007, power usage effectiveness (<a href="https://www.techtarget.com/searchdatacenter/definition/power-usage-effectiveness-PUE">PUE</a>) measures a data center's power consumption and assesses efficiency. It is the data center's total power divided by the power the equipment uses. The goal is to have the ratio come as close to one as possible, which indicates effective power usage. Networking equipment is among the many components found in data centers. Many networking devices, such as servers, switches, firewalls and routers, have environmentally friendly options.</li> <li><b>Carbon usage effectiveness.</b> The Green Grid also developed CUE, the ratio of carbon dioxide emissions a data center generates divided by the equipment's energy consumption. Much like PUE, CUE aims to have the lowest possible value. This indicates the data center and NOC effectively control carbon dioxide emissions and reduce the data center's carbon footprint.</li> </ol> </section> <section class="section main-article-chapter" data-menu-title="Green networking certifications"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Green networking certifications</h2> <p>In addition to PUE and CUE, two certifications are available to validate that a building or IT device is energy-efficient and environmentally friendly:</p> <ol class="default-list"> <li><b>Leadership in Energy and Environmental Design.</b> Developed by the U.S. Green Building Council, <a href="https://www.techtarget.com/searchdatacenter/definition/LEED-Leadership-in-Energy-and-Environmental-Design">LEED</a> is a building certification. LEED means a building has satisfied the criteria for lowering energy consumption and being environmentally friendly.</li> <li><b>Energy Star.</b> Developed by the U.S. Environmental Protection Agency and the U.S. Department of Energy, the Energy Star designation certifies a device's energy efficiency. Since 1992, Energy Star products have saved residential and business users <a target="_blank" href="https://www.energystar.gov/about?s=mega" rel="noopener">5 trillion kilowatt-hours of electricity</a>. In May 2025, the U.S. government announced plans to <a href="https://www.utilitydive.com/news/trump-administration-epa-energy-star-program/747351/">end the Energy Star program</a>.</li> </ol> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/green_certifications-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/green_certifications-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/green_certifications-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/green_certifications-f.png 1280w" alt="Popular green certifications" height="286" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>Figure 2. LEED and Energy Star certifications validate building and IT energy efficiency. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> </section> <section class="section main-article-chapter" data-menu-title="The benefits of green networking"> <h2 class="section-title"><i class="icon" data-icon="1"></i>The benefits of green networking</h2> <p>Energy consumption is one of the largest budget items of a data center. It's also among the top 10 issues that concern data center operators and, by extension, network operations managers.</p> <p>By committing to green networking, organizations can reap certain benefits. Over time, they could see a reduction in the following:</p> <ul class="default-list"> <li>Operating costs.</li> <li>Electricity consumption.</li> <li>Physical space.</li> <li>Carbon footprint.</li> <li>Carbon emissions.</li> <li>Water use.</li> <li>Waste output.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Green networks and the cloud"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Green networks and the cloud</h2> <p>The components in a green NOC are energy-efficient as compared to data centers without such operational and environmental controls. To go green, the network configuration does not need to change -- only the physical components.</p> <p>Migrating network components into a cloud or managed service provider environment can also increase the green factor. This eliminates the need for a physical NOC, as dashboards and other administrative tools can handle most network management tasks.</p> <p>Cloud service providers have grown in popularity, and many of the key providers, such as Amazon, Google and Microsoft, use environmentally friendly data centers. Many network service providers, such as local telephone companies, also institute green measures in their central offices.</p> </section> Green networking is the practice of selecting energy-efficient networking technologies and products to minimize resource use whenever possible. https://cdn.ttgtmedia.com/visuals/digdeeper/1.jpg https://www.techtarget.com/searchnetworking/definition/green-networking Mon, 07 Jul 2025 09:00:00 GMT What is green networking? <p>A host is a computer or other device that communicates with other hosts on a network. Also known as<i> network hosts</i>, hosts include <a href="https://www.techtarget.com/searchnetworking/definition/client-server">clients and servers</a> that send or receive data, services and applications.</p> <p>Hosts typically don't include intermediary network devices, such as <a href="https://www.techtarget.com/searchnetworking/definition/switch">switches</a> and <a href="https://www.techtarget.com/searchnetworking/definition/router">routers</a>, which are instead categorized as <a href="https://www.techtarget.com/searchnetworking/definition/node">nodes</a>. A<i> node </i>is a broader term that includes anything connected to a network, while a host requires an IP address. In other words, all hosts are nodes, but nodes are not hosts unless they require an Internet Protocol (IP) address to function.</p> <p>Hosts use various protocols to communicate, including Transmission Control Protocol (<a href="https://www.techtarget.com/searchnetworking/definition/TCP">TCP</a>) and <a href="https://www.techtarget.com/searchnetworking/definition/UDP-User-Datagram-Protocol">User Datagram Protocol</a>. On a <a href="https://www.techtarget.com/searchnetworking/definition/TCP-IP">TCP/IP</a> network, each host has a host number that, together with a network identity, forms its unique IP address. In the <a href="https://www.techtarget.com/searchnetworking/definition/OSI">Open Systems Interconnection</a> model, protocols in the <a href="https://www.techtarget.com/searchnetworking/definition/Transport-layer">transport layer</a> -- also known as Layer 4 -- are responsible for communication between hosts.</p> <section class="section main-article-chapter" data-menu-title="Types of IT hosts"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Types of IT hosts</h2> <p>Several other areas within IT use the term <i>host</i>, so it carries a slightly different meaning depending on the context. For example, a host can also be a device or program that provides services to smaller or less-capable devices or programs. The following are other major IT contexts that use hosts.</p> <h3>Web host</h3> <p>For companies or individuals with a website, a host is a <a href="https://www.techtarget.com/whatis/definition/Web-server">web server</a> that stores and transmits data for one or more websites. A <i>host</i> also refers to the service provider leasing this infrastructure, known as <i>hosting</i>.</p> <h3>Cloud host</h3> <p>Based on <a href="https://www.techtarget.com/searchcloudcomputing/definition/cloud-computing">cloud computing</a> technologies, a cloud host enables many servers to act as one system, in which multiple machines guarantee website performance. It often includes a network of servers pulling from different data centers in different locations.</p> <p>Cloud hosts operate as a service, enabling clients to buy as much of it as they need. Cloud hosting is an alternative to hosting a website on a single server. Cloud hosting is considered both infrastructure as a service and platform as a service. Using a <a href="https://www.techtarget.com/whatis/SaaS-IaaS-PaaS-Comparing-Cloud-Service-Models">public cloud model</a>, a public network transmits data physically stored on shared virtual servers that make up the cloud resource.</p> <h3>Virtual host</h3> <p>The term <i>virtual host</i> has two uses. One refers to technology used to run multiple domains or applications on a single physical server. The second refers to companies that sell virtual infrastructure services.</p> <h3>Remote host</h3> <p>In this context, users access a remote host in a different physical location using a private network or the internet. This process provides users with remote access. Examples include servers that users can log in to remotely or a host computer for a <a href="https://www.techtarget.com/searchenterprisedesktop/definition/remote-desktop">remote desktop</a>.</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineImages/networking-network_and_host_ids.jpg"> <img data-src="https://www.techtarget.com/rms/onlineImages/networking-network_and_host_ids_mobile.jpg" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineImages/networking-network_and_host_ids_mobile.jpg 960w,https://www.techtarget.com/rms/onlineImages/networking-network_and_host_ids.jpg 1280w" alt="Diagram of network hosts." height="425" width="520"> <figcaption> <i class="icon pictures" data-icon="z"></i>Hosts connect to other hosts and servers in this local network. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <h3>Host virtual machine</h3> <p>This refers to the hardware that provides computing resources to support virtual machines. This process is also known as <a href="https://www.techtarget.com/searchitoperations/definition/What-is-server-virtualization-The-ultimate-guide"><i>server virtualization</i></a>.</p> <h3>Mainframe computer environments</h3> <p>In this context, a mainframe computer can be the host provider of services for the workstations attached to it. This doesn't mean the host only has servers and the workstations only have clients. The server-client relationship is a programming model independent of this contextual usage.</p> <h3>Hostname</h3> <p>A hostname is a plaintext name identifying a host in a given domain. On a <a href="https://www.techtarget.com/searchnetworking/definition/local-area-network-LAN">local area network</a>, a server's hostname might be a nickname such as <i>mailserver1</i>. On the internet, a hostname makes up part of a web address and has three parts:</p> <ol class="default-list"> <li>Subdomain.</li> <li>Domain name.</li> <li>Top-level domain.</li> </ol> <p>For example, the hostname <i>subdomain.example.com</i> consists of the subdomain <i>subdomain</i>, the domain <i>example</i> and the top-level domain <i>.com</i>.</p> </section> A host is a computer or other device that communicates with other hosts on a network. https://cdn.ttgtmedia.com/visuals/digdeeper/3.jpg https://www.techtarget.com/searchnetworking/definition/host Mon, 07 Jul 2025 09:00:00 GMT What is a host (in computing)? <p>The Cisco Certified Network Associate certification is foundational for individuals seeking to build a career in networking. The CCNA 200-301 exam assesses the test-taker's ability to handle common networking tasks and understand the underlying concepts. Candidates have 120 minutes to complete the exam.</p> <p>Here is a breakdown of the exam domains and key subtopics, based on the official Cisco exam topics:</p> <ul class="default-list"> <li>Network fundamentals (20%).</li> <li>Network access (20%).</li> <li>IP connectivity (25%).</li> <li>IP services (10%).</li> <li>Security fundamentals (15%).</li> <li>Automation and programmability (10%).</li> </ul> <p>Networking fundamentals include the <a href="https://www.techtarget.com/searchnetworking/feature/7-types-of-networks-and-their-use-cases">different types of networks</a> and the models that explain how they work, such as the OSI and TCP/IP models. This section also digs into IP addressing, subnetting and basic configuration.</p> <p>The network access portion of the exam looks at <a href="https://www.techtarget.com/searchnetworking/tip/How-to-set-up-a-VLAN-for-enterprise-networks">virtual LAN (VLAN) configuration and troubleshooting</a>, trunking protocols and wireless network security. Exam candidates should also be familiar with Layer 2 discovery protocols, wireless access components and Cisco wireless architecture.</p> <p>IP connectivity is a crucial area that involves configuring and troubleshooting routing protocols, such as Open Shortest Path First (OSPF). The exam also explores <a href="https://www.techtarget.com/searchnetworking/feature/BGP-tutorial-The-routing-protocol-that-makes-the-Internet-work">basic Border Gateway Protocol (BGP) concepts</a>, such as peering and troubleshooting, routing tables and static routing.</p> <p>The IP services section of the 200-301 exam covers key applications that ride over IP networks, such as Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), Network Address Translation (NAT) and quality of service (QoS).</p> <p>When completing the section on security fundamentals, exam candidates will demonstrate their knowledge of security threats, vulnerabilities and mitigation techniques. This portion of the exam also dives into access control lists (ACLs), wireless security protocols and authentication concepts.</p> <p>Finally, the automation and programmability questions explore <a href="https://www.techtarget.com/searchnetworking/tip/12-network-automation-ideas-to-incorporate-in-your-network">automation's effect on network management</a>. Test-takers must demonstrate the ability to describe controller-based architectures, REST APIs and JSON-encoded data.</p> <p>Ready to test your networking knowledge? Take the quiz below.</p> <p><b>Editor's note: </b><i>An editor used AI tools to aid in the generation of this quiz. Our expert editors always review and edit content before publishing.</i></p> <p><i>Jennifer English is editorial director for Informa TechTarget's SearchNetworking, SearchCloudComputing, SearchITOperations and Network Computing sites.</i></p> <p> <script src="https://cdn.ttgtmedia.com/rms/editorial/HerNewQuiz.js"></script> <script src="https://cdn.ttgtmedia.com/quiz/quiz.js"></script> </p> Use this CCNA practice test as study material to prepare for the Cisco CCNA 200-301 exam. With 20 questions on a range of topics, we're not playing around. https://cdn.ttgtmedia.com/rms/onlineimages/certification_g483411626.jpg https://www.techtarget.com/searchnetworking/quiz/Cisco-CCNA-exam-Are-you-ready-Take-this-10-question-quiz-to-find-out Tue, 24 Jun 2025 16:45:00 GMT Cisco CCNA practice test: Try these 20 exam questions <p>In analog and digital communications, a signal-to-noise ratio -- often written S/N or SNR -- is a measure of the strength of a desired signal relative to background noise (unwanted interference). In this context, the term <i>signal</i> describes meaningful information, and <i>noise</i> refers to any disturbance that degrades the quality of the desired signal.</p> <p>SNRs are used in science and engineering to quantify signal clarity. SNR can be represented as a raw ratio (e.g., 100:1), but in technical specifications, the ratio is more commonly seen as a single numeric value that's expressed in decibels (dB). This approach takes advantage of the logarithmic scale and makes it easier to compare, calculate and interpret signal quality across different systems.</p> <p>Because almost all real-world systems operate in environments where noise is present, SNR is often used as a key performance indicator (<a href="https://www.techtarget.com/searchbusinessanalytics/definition/key-performance-indicators-KPIs">KPI</a>) to evaluate system quality and diagnose signal transmission problems. The ratio is also used as a benchmark for assessing improvements designed to compensate for signal <a href="https://www.techtarget.com/searchnetworking/definition/attenuation">attenuation</a>.</p> <section class="section main-article-chapter" data-menu-title="Why signal-to-noise ratio is important"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Why signal-to-noise ratio is important</h2> <p>Signal-to-noise ratio is an important KPI because it quantifies how accurately a desired signal can be distinguished from background noise. A higher SNR means the signal is clearer, while a lower SNR implies that noise levels are comparable to (or greater than) the signal.</p> <p>If the noise level is significantly higher than the strength of the desired signal, it can make meaningful information harder to detect, interpret and/or transmit reliably. On a practical level, excessive noise can disrupt data transfers for text files, audio files, graphics, <a href="https://www.techtarget.com/whatis/definition/telemetry">telemetry</a> applications, and audio or video streams:</p> <ul class="default-list"> <li>In analog signals, noise can directly corrupt the waveform, and this can lead to signal distortion and/or loss of information.</li> <li>In digital systems, excessive noise can result in high error rates, frequent retransmissions or total communication failure.</li> <li>In media applications, a high percentage of noise can distort audio, blur images and make it hard to discern details.</li> <li>In precision measurement systems, a negative SNR can mask critical data and reduce the accuracy of results.</li> <li>In communications systems, SNR can also affect channel capacity. Channel capacity refers to the maximum amount of data that can be transmitted reliably over that channel at any given time.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="What is the formula for SNR?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>What is the formula for SNR?</h2> <p>Signal-to-noise is a ratio, and ratios use division to compare two quantities. In the context of SNR, the ratio uses division to compare the strength of a desired signal to the level of background noise.</p> <figure class="main-article-image half-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/what_is_signal_to_noise_ratio-h.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/what_is_signal_to_noise_ratio-h_half_column_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/what_is_signal_to_noise_ratio-h_half_column_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/what_is_signal_to_noise_ratio-h.png 1280w" alt="The basic formula for determining signal-to-noise is the signal power divided by the noise power." height="209" width="279"> <figcaption> <i class="icon pictures" data-icon="z"></i>To determine the signal-to-noise ratio, divide the signal power by the noise power. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>The ratio of signal-to-noise can be expressed in raw power units or in decibels (dB). Signal-to-noise ratios expressed in raw power units are often used in educational settings to illustrate the fundamental concept of comparing signal strength to noise, without requiring logarithmic calculations. In contrast, signal-to-noise ratios expressed in decibels are standard in engineering and technical fields because they compress large ratios into a single numeric value on a logarithmic scale. A single numeric value can make comparisons between two or more ratios easier to understand.</p> </section> <section class="section main-article-chapter" data-menu-title="How do you calculate the signal-to-noise ratio?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How do you calculate the signal-to-noise ratio?</h2> <p>To calculate the signal-to-noise ratio, the first thing you need to do is to determine whether the signal and noise values are expressed in raw power units or decibels (dB).</p> <p>Ratios expressed in raw power units can be calculated by simply dividing the signal power by the noise power. Raw power values are typically expressed in <a href="https://www.techtarget.com/whatis/definition/watt">watts</a> (W) or milliwatts (mW). In cases where voltage is used to derive power, the square of the voltage (V²) might appear in calculations, especially when the circuit impedance is known.</p> <p>If both signal and noise values are expressed in decibels, the formula SNR(dB) = Signal(dB) - Noise(dB) is a common shortcut for expressing a signal-to-noise ratio as a single numerical value. This shortcut works because the decibel scale is base 10, and subtracting the noise level from the signal level is mathematically equivalent to dividing the raw power values and then applying a logarithmic formula. Decibel values are usually labeled with dB (decibels), dBm (decibels relative to 1 milliwatt) or dBW (decibels relative to 1 watt).</p> <figure class="main-article-image full-col" data-img-fullsize="https://www.techtarget.com/rms/onlineimages/calculating_signal_to_noise_ratio_in_decibels-f.png"> <img data-src="https://www.techtarget.com/rms/onlineimages/calculating_signal_to_noise_ratio_in_decibels-f_mobile.png" class="lazy" data-srcset="https://www.techtarget.com/rms/onlineimages/calculating_signal_to_noise_ratio_in_decibels-f_mobile.png 960w,https://www.techtarget.com/rms/onlineimages/calculating_signal_to_noise_ratio_in_decibels-f.png 1280w" alt="Signal-to-noise ratios can be calculated by subtracting the noise level from the signal level, as long as both values are expressed in decibels." height="224" width="560"> <figcaption> <i class="icon pictures" data-icon="z"></i>When signal and noise levels are both expressed in decibels, you can use subtraction to find the signal-to-noise ratio. This takes advantage of the fact that decibels represent ratios on a logarithmic scale. </figcaption> <div class="main-article-image-enlarge"> <i class="icon" data-icon="w"></i> </div> </figure> <p>It's important to use the right formula when calculating SNRs because the wrong formula will lead to invalid results. If you try to apply a decibel-based shortcut to values that are still in raw units, for example, the answer will be mathematically incorrect and won't reflect the true relationship between the signal and the noise. Similarly, if you use the logarithmic formula on values that are already in decibels, you'll essentially be applying the logarithm twice, which will also lead to an invalid result.</p> </section> <section class="section main-article-chapter" data-menu-title="How to interpret a signal-to-noise ratio"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How to interpret a signal-to-noise ratio</h2> <p>To interpret a signal-to-noise ratio accurately, you must first determine whether the ratio's value is positive, zero or negative.</p> <p>In general, a higher SNR corresponds to better signal clarity and reliability. For example, a high positive SNR (e.g., 20 dB or more) suggests acceptable signal quality with minimal interference. In contrast, a low positive SNR (e.g., around 2 dB) indicates marginal conditions that might result in poor signal transmissions and increased error rates.</p> <p>If the SNR is 0 dB, it means the signal and noise levels are equal, and a negative SNR means that the noise level exceeds the signal level.</p> </section> <section class="section main-article-chapter" data-menu-title="Is higher or lower SNR better?"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Is higher or lower SNR better?</h2> <p>In most contexts, a high signal-to-noise ratio is better because it indicates that the desired information stands out clearly. For example, a <a href="https://www.techtarget.com/searchmobilecomputing/definition/Wi-Fi">Wi-Fi</a> signal with SNR of 40 dB will deliver better network services than a signal that has a signal-to-noise ratio of 20 dB.</p> <p>It should be noted, however, that the advantages of a high SNR must be considered in context. For example:</p> <ul class="default-list"> <li>Increasing SNR can require greater power consumption, which might not be ideal for mobile or battery-operated devices.</li> <li>In medical settings, raising the SNR to achieve better image clarity can sometimes increase patient exposure to radiation.</li> <li>In consumer technologies, improvements beyond a certain SNR threshold might offer minimal benefits.</li> <li>In sensitive military or covert operations communication systems, excessively strong signals might become easier to detect or intercept.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="Signal-to-noise ratio: Applications and use cases across different fields"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Signal-to-noise ratio: Applications and use cases across different fields</h2> <p>SNR quantifies how clearly a desired signal stands out from background noise, but how this plays out in practice depends on the type of signal, the source of the noise and the goals of the system. Popular use cases for specific fields include the following:</p> <ul class="default-list"> <li><b>Audio engineering.</b> SNR is used to measure the clarity of sound in recording and playback systems. In this context, a high SNR indicates that the recorded sound is louder and clearer than any background hiss, hum or electronic interference. For high-fidelity audio systems, an SNR of 90 dB or more is indicative of accurate sound reproduction.</li> <li><b>Medical imaging.</b> SNR plays an important role in the diagnostic usefulness of magnetic resonance imaging (MRI), computed tomography scans (CT scans) and ultrasound images. Images with a higher SNR are more detailed and have higher contrast. This makes it easier for clinicians and artificial intelligence programming to detect abnormalities.</li> <li><b>Scientific measurement and instrumentation.</b> SNR determines the reliability of data collected from spectroscopy, seismology or astrophysics applications. In these fields, the challenge is often to reduce the environmental noise generated by the relevant hardware.</li> <li><b>Wireless communication.</b> A higher SNR allows for more efficient use of wireless bandwidth. If a Wi-Fi signal's S/N is too low, dropped <a href="https://www.techtarget.com/searchnetworking/definition/packet">packets</a> are likely to affect network performance. This can result in the need to retransmit data, which can, in turn, lead to higher <a href="https://www.techtarget.com/whatis/definition/latency">latency</a>.</li> <li><b>Digital image processing.</b> SNR can be used to assess the quality of images captured by sensors in cameras and other optical systems. A high SNR indicates that an image has little distortion or graininess, which is an important consideration for applications like surveillance, <a href="https://www.techtarget.com/searchenterpriseai/definition/facial-recognition">facial recognition</a> and <a href="https://www.techtarget.com/searchenterpriseai/definition/machine-vision-computer-vision">machine vision</a>. This is especially important in low-light conditions.</li> </ul> </section> <section class="section main-article-chapter" data-menu-title="SNR and the Shannon-Hartley theorem"> <h2 class="section-title"><i class="icon" data-icon="1"></i>SNR and the Shannon-Hartley theorem</h2> <p>SNR is also a KPI for determining channel capacity. Channel capacity is the maximum rate at which data can be transmitted over a noisy communication channel without error.</p> <p>The Shannon-Hartley theorem quantifies the maximum channel capacity mathematically by using the formula C=B log<sub>2</sub>(1+SNR).</p> <ul class="default-list"> <li>C is the channel capacity expressed in bits per second (<a href="https://www.techtarget.com/searchnetworking/definition/bits-per-second">bps</a>).</li> <li>B is the channel bandwidth expressed in hertz (<a href="https://www.techtarget.com/searchmobilecomputing/definition/hertz">Hz</a>).</li> <li>SNR is the signal-to-noise ratio expressed as a linear power ratio.</li> </ul> <p>It should be noted that as the SNR increases, the maximum achievable data rate also increases, but due to the logarithmic relationship, the returns diminish.</p> </section> <section class="section main-article-chapter" data-menu-title="How to improve SNR"> <h2 class="section-title"><i class="icon" data-icon="1"></i>How to improve SNR</h2> <p>Signal-to-noise ratios can be improved by increasing the strength of the desired signal and/or by reducing the background noise. One of the most common ways to improve SNR is to amplify the signal. Another strategy is to reduce the source of potential noise by shielding cables and components from electromagnetic interference (<a href="https://www.techtarget.com/searchmobilecomputing/definition/electromagnetic-interference">EMI</a>).</p> <p>Filtering and intelligent signal processing techniques can improve signal-to-noise ratios by removing unwanted frequency bands and smoothing out random noise. Using less crowded wireless channels can reduce <a href="https://www.techtarget.com/searchnetworking/definition/crosstalk">crosstalk</a> and interference from neighboring devices, which can also help improve SNR.</p> <p>In some high-performance systems, such as radio telescopes and deep-space communication arrays, internal noise can be minimized by cryogenically cooling the receiving circuitry to just a few degrees above absolute zero (minus 273.15°C or minus 459.67°F). This reduces thermal noise and allows the system to detect extremely faint signals from distant sources.</p> <p>Another technique is to average multiple signals. When the same signal is measured multiple times, its consistent features tend to become clearer, and random noise tends to cancel itself out.</p> </section> <section class="section main-article-chapter" data-menu-title="Using mesh networks to improve SNR"> <h2 class="section-title"><i class="icon" data-icon="1"></i>Using mesh networks to improve SNR</h2> <p>Ultimately, the most effective way to improve SNR depends on understanding the nature of the signal and the type of noise present. In many real-world scenarios, improving SNR involves a combination of environmental controls, intelligent signal processing and the strategic selection of network architecture to ensure reliable and efficient signal delivery.</p> <p>In general, wired networks tend to have higher SNRs than wireless networks. Implementing a mesh architecture can improve the signal-to-noise ratio in wireless networks.</p> <div class="youtube-iframe-container"> <iframe id="ytplayer-0" src="https://www.youtube.com/embed/8UZlwhiWKmA?autoplay=0&modestbranding=1&rel=0&widget_referrer=null&enablejsapi=1&origin=https://www.techtarget.com" type="text/html" height="360" width="640" frameborder="0"></iframe> </div> <p>While mesh networks don't directly amplify SNR by increasing signal power or eliminating noise directly, they enhance SNRs indirectly by shortening the transmission distance between devices/nodes and dynamically providing alternate routes that reduce the need for packet retransmissions. This adaptability helps maintain consistently high SNR KPIs across the network.</p> <p><i>SNR is also a key performance metric for evaluating the reliability, speed and quality of data transmission in </i><a href="https://www.techtarget.com/searchnetworking/tip/The-pros-and-cons-of-optical-wireless-communication"><i>optical wireless communication systems</i></a><i>.</i></p> </section> A signal-to-noise ratio compares the strength of a desired signal with any undesired signals created by background noise. https://cdn.ttgtmedia.com/visuals/digdeeper/4.jpg https://www.techtarget.com/searchnetworking/definition/signal-to-noise-ratio Tue, 03 Jun 2025 09:00:00 GMT What is signal-to-noise ratio and how is it measured? Search Networking Resources and Information from TechTarget 60 webmaster@techtarget.com