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.

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  • E

    What is an edge router?

    An edge router is a specialized router located at a network boundary that enables an internal network to connect to external networks.

  • F

    fault management

    Fault management is the component of network management that detects, isolates and fixes problems.

  • fax

    A fax -- short for 'facsimile' and sometimes called 'telecopying' -- is the telephonic transmission of scanned-in printed material, including text or images.

  • FCAPS (fault, configuration, accounting, performance and security)

    FCAPS (fault, configuration, accounting, performance and security) is a network management framework created by the International Organization for Standardization (ISO).

  • FDDI (Fiber Distributed Data Interface)

    FDDI (Fiber Distributed Data Interface) is a network standard that uses fiber optic connections in a local area network (LAN) that can extend in range up to 200 kilometers (124 miles).

  • fiber optics (optical fiber)

    Fiber optics, or optical fiber, refers to the technology that transmits information as light pulses along a glass or plastic fiber.

  • fiber to the home (FTTH)

    Fiber to the home (FTTH), also called fiber to the premises (FTTP), is the installation and use of optical fiber from a central point to individual buildings to provide high-speed internet access.

  • fiber to the x (FTTx)

    Fiber to the x (FTTx) is a collective term for various optical fiber delivery topologies that are categorized according to where the fiber terminates

  • file server

    A file server is a computer responsible for the storage and management of data files so that other computers on the same network can access the files.

  • File Transfer Access and Management (FTAM)

    File Transfer Access and Management (FTAM) is an OSI application Layer 7 protocol that standardizes how files are accessed and managed in a distributed network file system.

  • firewall as a service (FWaaS)

    Firewall as a service (FWaaS), also known as a cloud firewall, is a service that provides cloud-based network traffic analysis capabilities to customers as part of an overall cybersecurity program.

  • fixed-length subnet mask (FLSM)

    A fixed-length subnet mask (FLSM) refers to a type of enterprise or provider networking where a block of IP addresses is divided into multiple subnets of equal length (i.e., an equal number of IP addresses).

  • flooding (network)

    In a computer network, flooding occurs when a router uses a non-adaptive routing algorithm to send an incoming packet to every outgoing link except the node on which the packet arrived.

  • flow routing

    Flow routing is a network routing technology that takes variations in the flow of data into account to increase routing efficiency.

  • frame relay

    Frame relay is a packet-switching telecommunications service designed for cost-efficient data transmission for intermittent traffic between local area networks (LANs) and between endpoints in wide area networks (WANs).

  • frequency band

    In telecommunications, a frequency band -- sometimes called a band -- refers to a specific range of frequencies in the electromagnetic frequency spectrum assigned to certain applications.

  • frequency-division multiplexing (FDM)

    In frequency-division multiplexing (FDM), multiple signals are combined for transmission on a single communications line or channel, with each signal assigned to a different frequency (subchannel) within the main channel.

  • frequency-hopping spread spectrum (FHSS)

    Frequency-hopping spread spectrum (FHSS) transmission is the repeated switching of the carrier frequency during radio transmission to reduce interference and avoid interception.

  • frequency-shift keying (FSK)

    Frequency-shift keying (FSK) is a method of transmitting digital signals using discrete signals.

  • full-duplex

    Full-duplex data transmission means that data can be transmitted in both directions on a signal carrier at the same time.

  • What is FTP?

    File Transfer Protocol (FTP) is a network protocol for transmitting files between computers over TCP/IP connections.

  • G

    Generic Routing Encapsulation (GRE)

    Generic Routing Encapsulation (GRE) is a protocol that encapsulates packets in order to route various protocols over Internet Protocol (IP) networks.

  • geo-blocking

    Geo-blocking is blocking something based on its location.

  • gigabit (Gb)

    In data communications, a gigabit (Gb) is 1 billion bits, or 1,000,000,000 (that is, 10^9) bits. It's commonly used for measuring the amount of data that is transferred in a second between two telecommunication points.

  • Gigabit Ethernet (GbE)

    Gigabit Ethernet (GbE), a transmission technology based on the Ethernet frame format and protocol used in local area networks (LANs), provides a data rate of 1 billion bits per second, or 1 gigabit (Gb).

  • GMPLS (Generalized Multiprotocol Label Switching or Multiprotocol Lambda Switching)

    GMPLS (Generalized Multiprotocol Label Switching) is a networking technology that enables fast and reliable network switching of data flows on any type of network infrastructure.

  • graceful degradation

    Graceful degradation is the ability of a computer, machine, electronic system or network to maintain limited functionality even when a large portion of it has been destroyed or rendered inoperative.

  • green networking

    Green networking is the practice of selecting energy-efficient networking technologies and products and minimizing resource use whenever possible.

  • GVRP (GARP VLAN Registration Protocol or Generic VLAN Registration Protocol)

    GVRP (GARP VLAN Registration Protocol or Generic VLAN Registration Protocol) is a standards-based protocol that facilitates control of virtual local area networks (VLANs) within a larger network.

  • H

    HAProxy

    HAProxy is a high-performance, open source load balancer and reverse proxy for TCP and HTTP applications.

  • HDLC (High-level Data Link Control)

    HDLC (High-level Data Link Control) is a group of protocols or rules for transmitting data between network points (sometimes called nodes).

  • HELLO packet

    A HELLO packet is a special data packet (message) that is sent out periodically from a router to establish and confirm network adjacency relationships to other routers in the Open Shortest Path First (OSPF) communications protocol.

  • home server

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

  • host (in computing)

    A host is a computer or other device that communicates with other hosts on a network.

  • I

    IDSL

    IDSL is a hybrid of a digital subscriber line (DSL) and integrated services digital network (ISDN) technology that transmits data slightly faster than ISDN but much slower than most DSL services.

  • IEEE 802 wireless standards

    IEEE 802 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.

  • 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 nm to 1 mm.

  • ingress filtering

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

  • international private leased circuit (IPLC)

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

  • internet metering

    Internet metering is a service model in which an internet service provider (ISP) keeps track of bandwidth use and charges users accordingly.

  • IPTV (Internet Protocol television)

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

  • What is ICMP (Internet Control Message Protocol)?

    ICMP (Internet Control Message Protocol) is a network layer error-reporting protocol that's used to communicate data transmission problems.

  • What is IPv6 (Internet Protocol version 6)?

    Internet Protocol version 6 (IPv6) is a set of specifications from the Internet Engineering Task Force (IETF) that is responsible for identifying network devices and routing traffic across the internet.

  • J

    Joint Academic Network (JANET)

    The Joint Academic Network (JANET) is an internal, high-speed computer network that links the U.K. education and research community.

  • jumbo frames

    A jumbo frame is an Ethernet frame, or data packet, with a payload greater than the standard size of 1,500 bytes.

  • K

    Kbps (kilobits per second)

    In the U.S., Kbps stands for kilobits per second (thousands of bits per second) and is a measure of bandwidth (the amount of data that can flow in a given time) on a data transmission medium.

  • keystone jack

    A keystone jack is a female connector used in audio, video and data communications. It serves as a receptacle for a matching plug, which is a male connector of the same type as the jack.

  • L

    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.

  • Link Control Protocol (LCP)

    In computer networking, Point-to-Point Protocol (PPP) provides a standard way to transport multiprotocol data over point-to-point links; within PPP, Link Control Protocol (LCP) establishes, configures and tests data link internet connections.

  • load balancing

    Load balancing is a technique used to distribute network traffic across a pool of servers known as a server farm.

  • local area network (LAN)

    A local area network (LAN) is a group of computers and peripheral devices that are connected together within a distinct geographic area, such as an office building or campus.

  • location-based service (LBS)

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

  • logical network

    A logical network is a software-defined network topology or routing that is often different than the physical network.

  • loose coupling

    Loose coupling is an approach to interconnecting the components in a system, network or software application so that those components, also called elements, depend on each other to the least extent practicable.

  • M

    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 a data bit's state -- 0 or 1 -- is represented by the transition from one voltage level to another.

  • 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 that uses twisted-pair cabling to link two networked devices.

  • mean time to innocence

    Mean time to innocence is the average elapsed time between when a system problem is detected and any given team's ability to say the team or part of its system is not the root cause of the problem.

  • 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)

    Megahertz (MHz) is a unit multiplier that represents one million hertz (106 Hz). Hertz is the standard unit of frequency in the International System of Units (SI).

  • 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).

  • microsegmentation

    Microsegmentation is a security technique that splits a network into definable zones and uses policies to dictate how data and applications within those zones can be accessed and controlled.

  • millimeter wave (mmWave)

    Millimeter wave (mmWave), also known as millimeter band, is a range of electromagnetic frequencies between microwaves and infrared.

  • multi-user MIMO

    Multi-user MIMO, or 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.

  • multiplexing

    Multiplexing, or muxing, is a way of sending multiple signals or streams of information over a communications link at the same time in the form of a single, complex signal.

  • Multiprotocol Label Switching (MPLS)

    Multiprotocol Label Switching (MPLS) is a switching mechanism used in wide area networks (WANs).

  • mutual exclusion (mutex)

    In computer programming, a mutual exclusion (mutex) is a program object that prevents multiple threads from accessing the same shared resource simultaneously.

  • What is a MAC address and how do I find it?

    A MAC address (media access control address) is a 12-digit hexadecimal number assigned to each device connected to the network.

  • What is modulation?

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

  • N

    NACK (NAK, negative acknowledgment, not acknowledged)

    NACK, or NAK, an abbreviation for negative acknowledgment or not acknowledged, is a signal used by computers or other devices to indicate that data transmitted over a network was received with errors or was otherwise unreadable.

  • NBASE-T Ethernet

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

  • NBMA (non-broadcast multiple access)

    Non-broadcast multiple access (NBMA) is one of four network types in the Open Shortest Path First (OSPF) 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 a platform developed by Tenable that scans for security vulnerabilities in devices, applications, operating systems, cloud services and other network resources.

  • net neutrality

    Net neutrality is the concept of an open, equal internet for everyone, regardless of content consumed or the device, application or platform used.

  • 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).

  • 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 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 data used to manage and secure data networks.

  • network analyzer (protocol analyzer or packet analyzer)

    A network analyzer -- also called a network protocol analyzer or packet analyzer -- is a software application, dedicated appliance or feature set within a network component used in network performance troubleshooting or to enhance protection against malicious activity within a corporate network.

  • Network as a Service (NaaS)

    Network as a service, or NaaS, is a business model for delivering enterprise WAN services virtually on a subscription basis.

  • network assurance

    Network assurance is the method of validating whether services and policies configured on and across network appliances appropriately align with operational goals.

  • 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 Configuration Protocol (NETCONF)

    The Network Configuration Protocol (NETCONF) is an Internet Engineering Task Force (IETF) network management protocol that provides a secure mechanism for installing, manipulating and deleting the configuration data on a network device such as a firewall, router or switch.

  • network downtime

    Network downtime refers to inaccessibility to part or all of a network due to the failure of hardware, software or some combination of the two.

  • 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 a general term used to describe underlying data network infrastructure as a whole.

  • network functions virtualization (NFV)

    Network functions virtualization (NFV) is a network architecture model designed to virtualize network services that have traditionally run on proprietary, dedicated network appliances.

  • network hub

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

  • network interface card (NIC)

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

  • Network layer

    Located at Layer 3 of the Open Systems Interconnection (OSI) communications model, the primary function of the network layer is to move data into and through other networks.

  • network management

    A cornerstone of all computing is the ability to connect one machine, system or device to another -- enabling what is known as a computer network.

  • network management system

    A network management system, or NMS, is an application or set of applications that lets network engineers manage a network's independent components inside a bigger network management framework and performs several key functions.

  • network monitoring

    Network monitoring, also frequently called network management, is the practice of consistently overseeing a computer network for any failures or deficiencies to ensure continued network performance.

  • network node

    A computer network is a system of computers and computing devices that are connected via communication links.

  • network operating system (NOS)

    A network operating system (NOS) is a computer operating system (OS) that's designed primarily to support workstations, PCs and, in some instances, older terminals that are connected on a local area network (LAN).