Networking Definitions

This glossary explains the meaning of key words and phrases that information technology (IT) and business professionals use when discussing networking and related software products. You can find additional definitions by visiting WhatIs.com or using the search box below.

  • H

    home server

    A home server is a computer that functions as a server in a client-server home network.

  • HomeRF (home radio frequency)

    HomeRF (for home radio frequency) is a home networking standard developed by Proxim Inc.

  • hoot-n-holler

    In telecommunications, a hoot-n-holler is a dedicated "always on" connection used for two-way business-to-business voice communication.

  • host (in computing)

    A host (also known as "network host") is a computer or other device that communicates with other hosts on a network.

  • How do I...choose a VPN for my small business?

    A virtual private network (VPN)is a way to use a public telecommunication infrastructure, such as the Internet,to provide remote offices or individual users with secure access to their organization's network.

  • HTTP/2 protocol

    HTTP/2 protocol is the second version of HTTP, a network protocol used to define the format and transmission of data.

  • hybrid fiber coaxial network (HFC network)

    A hybrid fiber coaxial (HFC) network is a telecommunication technology in which optical fiber cable and coaxial cable are used in different portions of a network to carry broadband content (such as video, data, and voice).

  • hybrid SDN

    A hybrid SDN (software-defined network) is a network where both traditional networking and SDN protocols operate in the same environment.

  • hybrid WAN

    A hybrid WAN is a wide area network that sends traffic over two or more connection types. Hybrid WANs permit dynamic traffic engineering across both private and public domains, using a variety of connectivity options to make the best use of network resources.

  • network hub

    A network hub is a node that broadcasts data to every computer or Ethernet-based device connected to it.

  • I

    ICMP (Internet Control Message Protocol)

    ICMP (Internet Control Message Protocol) is an error-reporting protocol that network devices such as routers use to generate error messages to the source IP address when network problems prevent delivery of IP packets.

  • IDSL

    IDSL is a system in which digital data is transmitted at 128 Kbps on a regular copper telephone line (twisted pair) from a user to a destination using digital (rather than analog or voice) transmission, bypassing the telephone company's central office equipment that handles analog signals.

  • IEEE 802 wireless standards

    The IEEE 802 standard is a collection of networking standards that cover the physical and data-link layer specifications for technologies such as Ethernet and wireless.

  • IEEE 802.3

    802.3, or IEEE 802.3, is a working group of standard specifications for Ethernet, a method of packet-based physical communication in a local area network maintained by the Institute of Electrical and Electronics Engineers.

  • in-band signaling

    In the public switched telephone network, (PSTN), in-band signaling is the exchange of signaling (call control) information on the same channel that the telephone call itself is using.

  • infrared radiation (IR)

    Infrared radiation (IR), sometimes referred to simply as infrared, is a region of the electromagnetic radiation spectrum where wavelengths range from about 700 nanometers (nm) to 1 millimeter (mm).

  • infrared transmission

    Infrared transmission refers to energy in the region of the electromagnetic radiation spectrum at wavelength s longer than those of visible light, but shorter than those of radio

  • ingress filtering

    Ingress filtering is a method used by enterprises and internet service providers (ISPs) to prevent suspicious traffic from entering a network.

  • Intelligent Network (IN)

    Intelligent Network (IN) is a telephone network architecture originated by Bell Communications Research (Bellcore) in which the service logic for a call is located separately from the switching facilities, allowing services to be added or changed without having to redesign switching equipment.

  • Internet metering

    Internet metering is a service model in which an Internet service provider (ISP) tracks the customer's use of bandwidth and charges accordingly. Typically, the customer selects a service package with a flat rate up to a specified limit and pays, probably per gigabyte, beyond that limit... (Continued)

  • IPLC (international private leased circuit)

    An IPLC (international private leased circuit) is a point-to-point private line used by an organization to communicate between offices that are geographically dispersed throughout the world.

  • IPTV (Internet Protocol television)

    IPTV (Internet Protocol television) is a service that provides television programming and other video content using the TCP/IP protocol suite as opposed to traditional cable or satellite signals.

  • IPv6 (Internet Protocol Version 6)

    IPv6 is a set of specifications from the Internet Engineering Task Force that improves IPv4 by extending IP addresses from 32 bits to 128 bits.

  • IPX (Internetwork Packet Exchange)

    IPX (Internetwork Packet Exchange) is a networking protocol from Novell that interconnects networks that use Novell's NetWare clients and servers.

  • ISSU (in-service software upgrade)

    An ISSU (in-service software upgrade) is a technique for updating software on a network device without taking that device offline and thereby disrupting network services.

  • IT Survival Kit: Networking refreshers

    Quick Network Security & Hardware Refreshers School is out for college students across the US, but the learning never stops for IT professionals.

  • J

    Joint Academic Network (JANET)

    In the United Kingdom, JANET (Joint Academic Network) is the main backbone network for the UK university system of academic and research computers.

  • jumbo frames

    A jumbo frame is an Ethernet frame with a payload greater than the standard maximum transmission unit (MTU) of 1,500 bytes. 

  • K

    keystone jack

    A keystone jack is a female connector used in data communications, particularly local area networks (LANs).

  • kHz (kilohertz)

    The kilohertz, abbreviated kHz, is a unit of alternating current (AC) or electromagnetic (EM) wave frequency equal to one thousand hertz (1,000 Hz).

  • L

    LANDesk Client Manager (LDCM)

    LDCM (LANDesk Client Manager) is a software product from Intel that lets a system administrator for a local area network () see the configurations and monitor the status of personal computer on the LAN. LDCM is an implementation of the Desktop Management Interface (DMI) standard established by the Desktop Management Task Force, an industry group.

  • last-mile technology

    Last-mile technology is any telecommunications technology that carries signals from the broad telecommunication backbone along the relatively short distance (hence, the "last mile") to and from the home or business.

  • Layer Two Tunneling Protocol (L2TP)

    Layer Two Tunneling Protocol (L2TP) is an extension of the Point-to-Point Tunneling Protocol (PPTP) used by an Internet service provider (ISP) to enable the operation of a virtual private network (VPN) over the Internet.

  • Learning Path: Telephony and Wide Area Networks

    TELEPHONY AND WIDE AREA NETWORKS...circuit - PSTN - Plain Old Telephone Service (POTS) - telephone jacks - dial-up - acoustic coupler - modem - 56flex - 56 Kbps (x2) - handshaking - V.xx standards - local loop - central office - LIDB - dedicated line - BOC - RBOC - Intelligent Network (IN) - Advanced Intelligent Network (AIN) - Signaling System 7 (SS7) - EWSD - erlang (measure of line usage) - frame - frame relay - frame relay access device (FRAD) - ATM - 2600 - ISDN - B-channel - D-channel - terminal adapter - BISDN - HDLC - IDSL - PABX - Direct Inward Dialing (DID) - Automatic Number Identification (ANI) - Dialed Number Identification Service (DNIS) - permanent virtual circuit (PVC) - switched virtual circuit - DSLAM - Voice over IP - VoxML - CAPI - TAPI - splitter - splitterless (DSL) - ATU-R - digital loop carrier View other topics for self-study by visiting our Guide to the Learning Paths.

  • Link Control Protocol (LCP)

    In the Point-to-Point Protocol (PPP), the Link ControlProtocol (LCP) establishes, configures, and tests data-link Internet connections.

  • load balancing

    Load balancing is a technique used to distribute workloads uniformly across servers or other compute resources to optimize network efficiency, reliability and capacity.

  • local access and transport area (LATA)

    LATA (local access and transport area) is a term in the U.S. for a geographic area covered by one or more local telephone companies, which are legally referred to as local exchange carriers (LECs).

  • local area network (LAN)

    A local area network (LAN) is a group of computers and peripheral devices that share a common communications line or wireless link to a server within a distinct geographic area.

  • local loop

    In telephony, a local loop is the wired connection from a telephone company's central office in a locality to its customers' telephones at homes and businesses.

  • location-based service (LBS)

    A location-based service (LBS) is a software application for a mobile device that requires knowledge about where the mobile device is located.

  • logical network

    A logical network is one that appears to the user as a single, separate entity although it might in fact be either just a part of a larger network or an entity connecting multiple networks. A logical network is defined by its IP addressing scheme.

  • logical router

    A logical router is a configured partition of a traditional network hardware, or "physical," router.

  • long-haul optics

    Long-haul optics refers to the transmission of visible light signals over optical fiber cable for great distances, especially without or with minimal use of repeaters.

  • loopback test

    A loopback test is a test in which a signal in sent from a communications device and returned (looped back) to it as a way to determine whether the device is working right or as a way to pin down a failing node in a network.

  • loose coupling

    Loose coupling is a method of interconnecting the components in a system or network so that those components, also called elements, depend on each other to the least extent practicable... (Continued)

  • M

    MAC address (Media Access Control address)

    In a local area network (LAN) or other network, the MAC (Media Access Control) address is your computer's unique hardware number.

  • managed network services

    Managed network services are networking applications, functions and services that enterprises outsource to be remotely operated, monitored and maintained by a managed service provider (MSP).

  • Manchester encoding

    In data transmission, Manchester encoding is a form of digital encoding in which data bits are represented by transitions from one logical state to the other.

  • maximum segment size (MSS)

    The maximum segment size (MSS) is the largest amount of data, specified in bytes, that a computer or communications device can handle in a single, unfragmented piece.

  • maximum transmission unit (MTU)

    The maximum transmission unit (MTU) is the largest size frame or packet -- in bytes or octets (eight-bit bytes) -- that can be transmitted across a data link.

  • MDI/MDIX (medium dependent interface/MDI crossover)

    MDI/MDIX is a type of Ethernet port connection using twisted pair cabling.

  • mean opinion score (MOS)

    In voice communications, particularly Internet telephony, the mean opinion score (MOS) provides a numerical measure of the quality of human speech at the destination end of the circuit.

  • media access management

    In the Open Systems Interconnection (OSI) communication reference model, media access management is performed by the Media Access Control (MAC) sublayer of the Data-Link Layer.

  • megabits per second (Mbps)

    Megabits per second (Mbps) are units of measurement for network bandwidth and throughput. It is used to show how fast a network or internet connection is.

  • megahertz (MHz)

    The megahertz, abbreviated MHz, is a unit of alternating current (AC) or electromagnetic (EM) wave frequency equal to one million hertz (1,000,000 Hz).

  • metropolitan area network (MAN)

    A metropolitan area network (MAN) is a computer network that is larger than a single building local area network (LAN) but is located in a single geographic area that is smaller than a wide area network (WAN).

  • MHz

    The megahertz, abbreviated MHz, is a unit of alternating current (AC) or electromagnetic (EM) wave frequency equal to one million hertz (1,000,000 Hz).

  • microsegmentation

    Microsegmentation is a technique used to divide a network into logical and secure units through the application of policies that dictate how data and applications are accessed and controlled.

  • Microsoft Network Access Protection (NAP)

    Network access protection (NAP), introduced with Windows Server 2008, is Microsoft’s approach to controlling access to a network based on a determination of each device’s health.

  • microwave

    The term microwave refers to electromagnetic energy having a frequency higher than 1 gigahertz (billions of cycles per second), corresponding to wavelength shorter than 30 centimeters.

  • millimeter wave (MM wave)

    Millimeter wave (MM wave), also known as millimeter band, is the band of spectrum with wavelengths between 10 millimeters (30 GHz) and 1 millimeter (300 GHz).

  • Mininet

    Mininet is a software emulator for prototyping a large network on a single machine. 

  • modem error-correcting protocols

    The protocols that modems agree on and use for checking and correcting transmission errors have evolved toward accuracy, speed, and efficiency since 1978 when the Xmodem protocol became a de facto standard.

  • modem lights (AA)

    This page provides a description of the abbreviations and meanings of each of the lights that describe the "handshaking" between a computer modem and the UART chip in a computer.

  • modulation

    Modulation is the process of converting data into radio waves by adding information to an electronic or optical carrier signal.

  • Morse code

    Morse code is a method of sending text messages by keying in a series of electronic pulses, usually represented as a short pulse (called a "dot") and a long pulse (a "dash").

  • MPLS-TP (MPLS Transport Profile)

    The Multiprotocol Label Switching Transport Profile (MPLS-TP) is a protocol extension of MPLS designed to speed up and shape network traffic in operator transport networks.

  • mrouter (multicast router)

    An mrouter, or multicast router, is a router program that distinguishes between multicast and unicast packets and determines how they should be distributed along the Multicast Internet (sometimes known as the Multicast Backbone or MBone).

  • multi-user MIMO

    Multi-user MIMO (MU-MIMO) is a wireless communication technology that uses multiple antennas to improve communication by creating multiple connections to the same device at the same time

  • multicast

    Multicast is communication between a single sender and multiple receivers on a network.

  • multihomed

    Multihomed describes a computer host that has multiple IP addresses to connected networks.

  • multiplexing

    Multiplexing is the simultaneous sending of multiple information streams over a communications medium as a single, complex signal that is then recovered at the receiving end.

  • Multiprotocol Label Switching (MPLS)

    Multiprotocol Label Switching (MPLS) is a protocol-agnostic routing technique designed to speed up and shape traffic flows across enterprise wide area and service provider networks.

  • mutex (mutual exclusion object)

    In computer programming, a mutex (mutual exclusion object) is a program object that is created so that multiple program thread can take turns sharing the same resource, such as access to a file.

  • mux

    In communication transmission systems, mux (pronounce muks, sometimes spelled "MUX") is an abbreviation for multiplexing, a device that sends multiple signals on a carrier channel at the same time in the form of a single, complex signal to another device that recovers the separate signals at the receiving end.

  • N

    Nagle's algorithm

    Named for its creator, John Nagle, the Nagle algorithm is used to automatically concatenate a number of small buffer messages; this process (called nagling) increases the efficiency of a network application system by decreasing the number of packets that must be sent.

  • NAK (negative acknowledgment or not acknowledged)

    NAK is an abbreviation for negative acknowledgment or not acknowledged.

  • NBAR (Network Based Application Recognition)

    Network Based Application Recognition (NBAR) is a mechanism that classifies and regulates bandwidth for network applications to ensure that available resources are utilized as efficiently as possible. Cisco Systems developed NBAR as part of its Content Networking platform for implementing intelligent network services... (Continued)

  • NBASE-T Ethernet

    NBASE-T Ethernet is an IEEE standard and Ethernet-signaling technology that allows existing twisted-pair copper cabling to exceed the cable's specified limit of 1 Gbps for distances of up to 100 meters.

  • NBMA (non-broadcast multiple access)

    NBMA (non-broadcast multiple access) is one of four network types in the OSPF (Open Shortest Path First) communications protocol.

  • near-end crosstalk (NEXT)

    Near-end crosstalk (NEXT) is an error condition that can occur when connectors are attached to twisted pair cabling.

  • Nessus

    Nessus is an open-source network vulnerability scanner that uses the Common Vulnerabilities and Exposures architecture for easy cross-linking between compliant security tools.

  • Net Neutrality

    Net neutrality is the principle that data packets on the Internet should be moved impartially, without regard to content, destination or source.

  • NetBIOS (Network Basic Input/Output System)

    NetBIOS (Network Basic Input/Output System) is a network service that enables applications on different computers to communicate with each other across a local area network (LAN).

  • NETCONF

    NETCONF is an IETF network management protocol that provides an administrator or network engineer with a secure way to configure a firewall, router, switch or other network device.

  • NetOps

    NetOps, also referred to as NetOps 2.0, is a networking approach that encompasses the use of DevOps tools, methods and techniques to create an agile, scalable and programmable infrastructure capable of delivering business-critical applications and services rapidly and efficiently.

  • NetScaler (SDX)

    Citrix NetScaler SDX is a service delivery networking platform for enterprise and cloud datacenters. NetScaler SDX supports multiple NetScaler instances on a single hardware appliance.

  • network access control (NAC)

    Network access control (NAC), also called network admission control, is a method to bolster the security, visibility and access management of a proprietary network.

  • network access server (NAS)

    A network access server (NAS) is a computer server that enables an independent service provider (ISP) to provide connected customers with Internet access.

  • Network Address Translation (NAT)

    A Network Address Translation (NAT) is the process of mapping an internet protocol (IP) address to another by changing the header of IP packets while in transit via a router.

  • network analytics

    Network analytics is the application of big data principles and tools to the management and security of data networks.

  • network analyzer (protocol analyzer or packet analyzer)

    A network analyzer is a combination of hardware and programming, or in some cases a stand-alone hardware device, that can be installed in a computer or network to enhance protection against malicious activity... (Continued)

  • Network as a Service (NaaS)

    Network as a service (NaaS) is a business model for delivering enterprise-wide area network services virtually on a subscription basis.

  • network automation

    Network automation is a methodology in which software automatically configures, provisions, manages and tests network devices.

  • network configuration management (NCM)

    Network configuration management is the process of organizing and maintaining information about all of the components in a computer network.

  • network engineer

    A network engineer is a technology professional who has the necessary skills to plan, implement and oversee the computer networks that support in-house voice, data, video and wireless network services.

  • network fabric

    Network fabric is an industry term that describes a network topology in which devices pass data to each other through interconnecting switches.

  • network functions virtualization (NFV)

    Network functions virtualization (NFV) is an initiative to virtualize network services traditionally run on proprietary, dedicated hardware.

  • network hypervisor

    A network hypervisor is a program that provides an abstraction layer for network hardware.  Network hypervisors allow network engineers to create virtual networks that are completely decoupled and independent from the underlying physical network.

  • network interface card (NIC)

    A network interface card (NIC) is a hardware component, typically a circuit board or chip, that is installed on a computer so that it can connect to a network.

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