negative acknowledgment. Response sent from a receiving device to a sending device indicating that the information received contained errors.
Server connected to a network that resolves network names into network addresses.
network access server. A platform (or collection of platforms, such as an AccessPath system) that interfaces between the packet world (for example, the Internet) and the circuit world (for example, the PSTN). See also access device.
Network Address Translation. Mechanism for reducing the need for globally unique IP addresses. NAT allows an organization with addresses that are not globally unique to connect to the Internet by translating those addresses into globally routable address space. Also known as Network Address Translator.
Network Control Protocol. Series of protocols for establishing and configuring different network layer protocols, such as for AppleTalk over PPP. See also PPP.
In OSPF, two routers that have interfaces to a common network. On multiaccess networks, neighbors are discovered dynamically by the OSPF Hello protocol.
NetBIOS Extended User Interface. Enhanced version of the NetBIOS protocol used by network operating systems, such as LAN Manager, LAN Server, Windows for Workgroups, and Windows NT. NetBEUI formalizes the transport frame and adds additional functions. NetBEUI implements the OSI LLC2 protocol. See also LLC2 and OSI.
Network Basic Input/Output System. API used by applications on an IBM LAN to request services from lower-level network processes. These services might include session establishment and termination, and information transfer.
A feature of some routers that allows them to categorize incoming packets into flows. Because packets in a flow often can be treated in the same way, this classification can be used to bypass some of the work of the router and accelerate its switching operation.
Popular distributed NOS developed by Novell. Provides transparent remote file access and numerous other distributed network services.
Collection of computers, printers, routers, switches, and other devices that can communicate with each other over some transmission medium.
Network layer address referring to a logical, rather than a physical, network device. Also called a protocol address. Compare with MAC address.
Person responsible for the operation, the maintenance, and the management of a network.
Hardware or software device offering various network troubleshooting features, including protocol-specific packet decodes, specific preprogrammed troubleshooting tests, packet filtering, and packet transmission.
Generic term used to describe systems or actions that help maintain, characterize, or troubleshoot a network.
Part of an IP address that specifies the network to which the host belongs.
Network File System. As commonly used, a distributed file system protocol suite developed by Sun Microsystems that allows remote file access across a network. In actuality, NFS is simply one protocol in the suite. NFS protocols include NFS, RPC, XDR, and others. These protocols are part of a larger architecture that Sun refers to as ONC.
Next Hop Resolution Protocol. Protocol used by routers to dynamically discover the MAC address of other routers and hosts connected to an NBMA network. These systems then can communicate directly without requiring traffic to use an intermediate hop, increasing performance in ATM, Frame Relay, SMDS, and X.25 environments.
Network interface card. Board that provides network communication capabilities to and from a computer system. Also called an adapter.
National Institute of Standards and Technology. U.S. government organization that supports and catalogs a variety of standards. Formerly the NBS
network management system. System responsible for managing at least part of a network. An NMS is generally a reasonably powerful and well-equipped computer, such as an engineering workstation. NMSs communicate with agents to help keep track of network statistics and resources.
network operations center. Organization responsible for maintaining a network.
Resource-intensive OSPF area that carries a default route, static routes, intra-area routes, interarea routes, and external routes. Nonstub areas are the only OSPF areas that can have virtual links configured across them, and are the only areas that can contain an ASBR. Compare with stub area.
National Science Foundation. U.S. government agency that funds scientific research in the United States. The now-defunct NSFNET was funded by the NSF.
network termination 1. In ISDN, a device that provides the interface between customer premises equipment and central office switching equipment.
Network Time Protocol. Protocol built on top of TCP that ensures accurate local time-keeping with reference to radio and atomic clocks located on the Internet. This protocol is capable of synchronizing distributed clocks within milliseconds over long time periods.