Network Glossary



Software that runs on the client that enables the client to be managed. Also called Management Agent.


A server or other computer that is designed for a highly specialized, dedicated use, such as Web hosting or Web storage. Appliances are often low-cost and easy to implement.

Application Server

A server that runs between clients and back-end business applications and databases. It handles application logic, determining how the business system should behave. Also called an appserver.

Asynchronous Transfer Mode (ATM)

A switched network transmission technology that is highly scalable and provides typical speeds of up to 644 Mbps. ATM services are highly reliable and commonly include Quality of Service (QoS) guarantees. See also Frame Relay, Dedicated Leased Line.



In digital systems, the speed of transmission of a communications line, measured in bits per second (bps). For example, a modem with a data speed of 57,600 bps has twice the bandwidth of a modem with a data speed of 28,800 bps. (2) In analog systems, the difference, expressed in hertz (Hz) between the highest and the lowest frequencies of a range of frequencies. For example, a telephone has a bandwidth of 3,000 Hz, which is the difference between the lowest (300 Hz) and the highest (3,300 Hz) it can accommodate.


A pathway between devices. On a network, the bus is the circuit that manages the transmission of data to devices across the LAN. In a PC, the bus provides the data transfer path between the CPU and memory and peripheral devices. Typical PC buses include: USB, PCI, AGP and Firewire.


Cable Modem Service

A service that delivers high-speed internet access to businesses and consumers over cable lines. A separate cable modem or router is usually required to use the service. See also: DSL, ISDN, Frame Relay, Dedicated Leased Line and T1/T3.


A temporary storage place; pronounced “cash”. Cache is generally used to speed up data transfer performance. For example, a Web browser may use a cache to store commonly accessed pages, so they can be retrieved from the cache instead of from the Internet, allowing them to be accessed more quickly.

Category 5 Cable (Cat5)

The wire most commonly used in Ethernet LANs. It connects computers and devices to an Ethernet network. See also Twisted Pair.

Central Processing Unit (CPU)

The part of a computer that includes the circuits that interpret and execute instructions. The CPU, or microprocessor, is the “brain” of the computer.


A computer system that requests access to the data, services or resources of a server (another computer system). Multiple clients may share access to a common server.

Client/Server Network

A network set-up in which one of more computers – the clients – make service requests from a computer called the server, which fulfills them. Most business applications written today are designed for the client/server network model. See also Peer-to-Peer Network.


The act of linking two or more computers together so they behave like a single unit. Clustering is used commonly for load balancing, fault-tolerance and parallel processing.

Coaxial Cable

A cable consisting of one conductor, usually a small copper wire, within and insulated from another conductor of larger diameter, usually copper tubing or copper braid.

Communication Server

The hardware and software that handles user requests to access a network remotely. Also called a remote access server. Also called a Remote Access Server.


Data Warehouse

An aggregate of information from various resources stored centrally to provide flexible and efficient access to data. Many organizations keep a data warehouse to maintain large amounts of business data, such as transaction histories and analyze it to help support business decisions.

Data Warehousing

The act of storing information in a data warehouse.

Database Server

A server on a LAN that is dedicated to storing and retrieving information from databases.

Dedicated Leased Line

A data channel that permanently connects two or more locations that is always kept on. Dedicated leased lines are commonly used for connecting geographically distant businesses and for accessing the Internet because they support fast and secure data transfer. See also Cable Modem Service, DSL, ISDN, Frame Relay and T1/T3.

Digital Subscriber Line (DSL)

A technology that delivers high-speed Internet access to businesses and consumers over ordinary copper telephone line. A separate DSL modem or router is usually required to use the service. See also: Cable Modem Service, ISDN, T1/T3, Dedicated Leased Line and Frame Relay.


The process of duplicating information from one set of drives to another so that an exact copy of the data always exists. Similar to mirroring. See Also RAID.



A business approach in which some or all of the sales and customer support processes are managed electronically, usually via the Internet.

Email Server

A server that manages email communications. An email server accepts and manages incoming mail and stores and forwards outgoing mail.

Enterprise Management

Management of the total heterogeneous network.


The most common type of LAN access technology. The most common kind of Ethernet is 10/100, meaning it supports both 10Base-T (transmission speeds up to 10 Mbps). See also Twisted Pair, Category 5 Cable, Token Ring.


A private network that uses internet infrastructure to connect a business securely with outside customers and business partners. Firewalls and encryption technology “privatize” a slice of the public network to allow companies to exchange data confidentially.


File Server

A server that stores programs and data files shared by users on a network.


A set of security tools designed to separate an internal network from the public Internet in order to keep unauthorized users out of a restricted network. Firewalls are the primary line of security defense for businesses.

Form Factor

The size, shape and configuration of a computer hardware object. The term is often used to describe the size of a computer case or chassis. It can also be applied to internal components such as disk drives and circuit boards.

Frame Relay

A transmission technology used to connect two networks or provide Internet access at speeds from 56 Kbps (typical analog modem speed) up to 44.6 Mbps. Frame relay uses T1, T3 or other digital leased lines for access, but unlike typical dedicated leased lines, it can portion varying amounts of bandwidth as needed by the network. See also Cable Modem Service, ISDN, T1/T3, DSL.


Gigabit Ethernet

An Ethernet technology that transmits data at a rate of 1 billion bits (1 Gigabit) per second.

Graphical Console Direction

The Ability to control a server remotely using a graphical operating environment from an alternate location. Works with Microsoft Windows 2000 and Windows NT.


Hot Swap

The replacement of a device such as a hard drive or data storage drive while a computer systems remains in operation. During a hot swap the computer perceives that the device is still in use while it is being removed and replaced so that rebooting the computer is not necessary to make the device functional.


A piece of hardware that receives and forwards data between computers or other devices on a network. See also: Router, Switch.


In Band

The state of a server when it is operational.

Integrated Services Digital Network (ISDN)

A communications technology that enables digital transmission over ordinary telephone lines. Typical ISDN Internet access operates at 128 Kbps, slower than comparable DSL or cable modem service. See also Cable Modem Service, DSL, T1/T3, Dedicated Leased Line, Frame Relay


A shared boundary between external connections that links differing systems, programs or devices. It allows these connections to work together and exchange information.

Internet Service Provider (ISP)

A company that provides businesses and individuals with access to the Internet for Web browsing and email. Many ISPs also offer Web site hosting services. Users of ISP services can connect to the Internet via a dial-up modem or through broadband connections such as Cable Modem Service, DSL, or T1/T3 lines.


A private network that allows users in a company to access data using a Web browsers. It looks like a World Wide Web site but is strictly internal and doesn’t actually connect to the Internet



The core of an operating system. It performs basic functions such as allocating hardware resources and managing memory.

Knowledge Management

The management of a company’s in-house knowledge base to facilitate data mining and effective information sharing throughout the organization.

Keyboard, Video and Mouse Capability (KVM)

KVM is essential in confined computer areas where having a separate monitor, keyboard, and mouse dedicated to each server is impractical. It allows you to configure and manage the server using the keyboard, monitor and mouse of another computer.



The amount of lag time that results when data is moved from one designated point to another. The term is used to refer to a delay in response when moving data in a network or single computer system. In general, the more traffic your network gets, the greater the latency will be.


A Unix-based computer operating system whose kernel was developed by Linus Torvalds. Linux is an open-source software. See also Windows NT/2000, Netware, Network Operating System, UNIX.

Load Balancing

The process of dividing a single server’s workload between two or more servers to improve efficiency, and ultimately serve users faster.

Local Area Network (LAN)

A computer network for geographically concentrated users, such as those in an office building. A LAN Permits them to share software applications such as email and hardware devices such as printers. A LAN can either be peer-to-peer based or client/server based.


Management Agent

See Agent


The component of the computer’s motherboard that interprets and executes instructions. The microprocessor, or CPU, is the “brain” of the computer.


One: The process of copying information from one computer to another in order to reduce network traffic and/or ensure availability of the sites or files. Users close to a mirror can retrieve data more quickly than they would be able to if their request had to be sent to and returned from a more distant originating computer.

Two: The process of duplicating data on one hard drive to another hard drive on the same computer/server so that each hard drive has the same information. In this way, if one of the hard drives fail, the second one is available for redundancy. Mirroring is a type of RAID.


A device that enables a computer to transmit data over telephone lines. A modem converts the digital data that computers store into the analog waves that telephone lines transmit. Modem is an acronym for modulator-demodulator.



Novell’s network operating system

Network Attached Storage (NAS)

Hard disk storage that provides shared data to clients and servers on a LAN. NAS has separate network address from the LAN computer that serves applications to users. This setup allow application programs and files to be served faster because they rely on different processor resources.

Network Interface Card (NIC)

A circuit board that is installed in a client or a server to enable it to connect to a network. Also called a network adapter.

Network Operating System (NOS)

A computer operating system designed to support a network of workstations. It provides peripheral, application and database sharing across the network. Common NOSs are Windows NT/2000, Novell NetWare and Linux.


Open-Source Software

Software that is freely available and can be modified by users.

Operating System (OS)

The computer program that manages all application programs on a computer. It handles tasks such as determining which applications should run, the order they should run in, and how much internal memory they have allocated to them. The OS also communicates with users about operation status and errors.

Out of Band

The state of a server when it is not operational due to hardware failure or scheduled maintenance.



A device on a peer-to-peer network. Each peer has equal responsibility in the network and operated with the same amount of power.

Peer-to-Peer Network

A network structure in which each workstation has equivalent capabilities. Peer-to-peer networks are an alternative to client/server networks. In general, they are simpler to set up and maintain but do not offer the same level of security or functionality. See also Local Area Networks.


A computer or network device that is added to the core elements of a computer. Some can be included in the main computer itself, such as a CD-ROM drive; others, such as a printer, are attached to a computer’s ports by cables or accessed through a shared network. A computer’s bus allows peripherals to communicate with the CPU.

Plug and Play

An Intel standard for the design of PC expansion boards. It enables computers to recognize new peripheral devices without having to undergo additional configuration.


Sockets and/or plugs that physically connect computer devices or peripherals, such as hard drives and printers A personal computer typically comes with ports built into it. Some ports that are commonly used today are: Serial, Parallel, PS/2 and USB.



A free-standing framework that holds network hardware components such as servers and hubs.

Rack-Mount Server

A server with a form factor that is designed to fit inside an industry-standard 19-inch rack. The thickness of a rack-mount server is usually designated by unit size (U).

Random Access Memory (RAM)

The memory that temporarily stores program data actively running on a computer. Data stored in RAM is available only as long as a computer stays on. As soon as the computer is turned off, the data disappears. This is why files must be saved in more permanent storage places (hard disks, floppy disks, etc.) In order to be retrieved after a computer is turned off. Computers load active programs into RAM rather than hard drives or floppy disks so they can access the data much faster. RAM is typically measured in Megabytes or MB, and most computers today come with 64 to 128 MB of RAM.


Duplication of components and connections in a system to reduce or avoid the occurrence of system failures. For example, a redundant Internet connection provides immediate backup in the event that the primary connection fails.

Redundant Array of Inexpensive Disks (RAID)

The strategy of storing the same data in different places on multiple hard disks to improve system performance and protect data. RAID appears as a single logical hard disk to the operating system. There are several types of RAID, including RAID 1 or Mirroring.

Remote Access

The ability to connect to a computer or network from outside the network, usually via a telephone or cable line, or through a dedicated connection such as a T1 line. Users of remote access capabilities include telecommuters, traveling staff and other long-distance business affiliates. See also VPN.

Remote Access Server (RAS)

A server with modems that also users to connect to the network using phone lines.

Remote Power Up

The ability to reboot the server from an offsite location.

Remote Support

The ability to run diagnostic programs and manage system troubleshooting from a remote location.


A network device that determines where information packets traveling between networks should be directed by communicating with other routers and configuring the best route between any two hosts. Routers are located at the points where networks meet. See also:

Hub, Switch.



The ability for hardware and/or software to accommodate usage growth. Most companies consider scalability a desirable attribute because it allows them to invest in hardware and software that can grow with their businesses, rather than becoming obsolete as changes occur.


A standard bus or interface between a computer and peripheral devices such as printers and disk drives. SCSI ports are supported by all major operating systems. SCSI stands for Small Computer Interface and is pronounced “skuzzy.” See also USB.


A computer that provides shared services to other computers and resources over a network.


A network device that “learns” of devices that are attached to it and send data intelligently though a network to its destination. Unlike hubs, switches consider network information to determine the most efficient path for sending data to its destination. See also Hub, Router.


T1/T3 Connection

High-speed connections used by businesses or ISP’s to access the Internet. A T1 line operates at 1.544 Mbps. A T3 line operates at 44.736 Mbps. See also Cable Modem Service, DSL, ISDN, Dedicated Leased Line and Frame Relay.


A person who works from home by electronically connecting to the company network.

Token Ring

A type of LAN access technology based on a token ring (closed loop) topology. It transfers data across the network by passing a token from one resource to the next in a loop until it meets its finale destination on the loop. See also Ethernet.


The physical arrangement of how devices are connected on a LAN or between two LANs. Common topologies include star, token ring and bus.

Transmission Control Protocol/Internet Protocol (TCP/IP)

The basic communication language of the Internet. TCP/IP is a set of protocols that move data from one computer to another by transmitting it in packets and reassembling it on the other side. All computers that interact directly with the Internet use the TCP/IP protocols.

Twisted Pair

The standard copper wire used to connect homes and businesses to telephone service. A high grade of twisted wire is often used to wire LANs because it is less expensive than coaxial cable. The twisted pair wire typically used in LANs is Category 5 cable or Cat5.


Uninterruptible Power Supply (UPS)

A device that provides protection from power outages and surges. It contains a battery that keeps a computer operating for a short time when power is lost allowing data to be saved and the computer to be properly shut down before damage occurs. Some UPSs come with software that intelligently shuts down a computer if there is an extended power outage, thereby automatically protecting data and the computer.

Universal Serial Bus (USB)

A plug-and-play bus or interface that allows peripheral devices such as printers and scanners to be added to a computer without an adapter card. Most PC models today include USB ports. USB ports have replaced serial and parallel ports as a faster way of connecting devices to a computer. A USB operates at speeds up to 12 Mbps; USB 2.0, which was recently released, operates at speeds of up to 480 Mbps.


A computer operating systems developed by AT&T’s Bell Labs. Unix is an open system that can be modified by users such as individuals, universities and companies. Also see Linux.


Virtual Private Network (VPN)

A technology that allows private, secure network connections between remote locations over the Internet. A VPN appears as a private network to the customer but uses the public network as its backbone. See also Remote Access.


Web Server

A server that delivers Internet pages to computers that request them.

Wide Area Network (WAN)

A computer network whose components are farther apart than those in a LAN. A WAN typically includes multiple LANs and utilizes public connections, such as the telephone system or the Internet.

Windows NT/2000

Microsoft’s most sophisticated network operating system. There are two versions of Windows NT: Windows NT Server, which is designed to act as a network server, and Windows NT Workstation for stand-alone or client workstations.

Wireless Access Station

A device that connects wireless devices, including PCs to a network.

Wireless LAN

A LAN that uses a wireless radio technology in place of cables to connect clients to the network.


A group of users involved in common projects who share computer files, usually over a LAN.