A message database where people can log in and leave broadcast messages for others grouped (typically) into topic groups.

A device or an area of memory used for temporary storage when transmitting data from one device to another. Compensates for a difference in rate of data flow or in time of occurrence of events. Used on routing nodes to temporarily store data that is to be forwarded from one node to another.

The number of buffers provided at one time by the network software to handle data. Level can be single or multiple. Single buffering tends to be less efficient than multibuffering but uses less memory on the local system. Multibuffering provides bett er performance, and a network can send or process several buffers of data in quick succession.

(1) A LAN topology in which all nodes connect to a single transmission medium. All nodes are equal, and all nodes hear all transmissions on the medium. Bus topologies are reliable because failure of a node does not affect the ability of other nodes to transmit and receive. (2) A flat, flexible cable consisting of many transmission lines or wires used to interconnect computer system components to provide communication paths for addresses, data, and control information.

A portion of a computer's RAM reserved to act as a temporary memory for items read from a disk. These items become instantly available to the user.

A BIND server that has no authority for any zone; acquires information in the process of resolving clients' queries and stores it in its cache. See also BIND server , forwarder server , primary server , and secondary server .

The main or official name for a host; other names for the same host are aliases. In a BIND configuration, you specify th e canonical name in a CNAME record of the named.hosts file.

A BIND configuration logging statement phrase that specifies the different categories for which to log messages. Categories include: config , parser , queries , lame-servers , statistics , panic , update , ncache , xfer-in , xfer-out , db, eventlib , packet , cname , security , os , insist , maintenance , load , response-checks , and default .

A form of network management that manages from a single point in the network.

The data pa th between two or more stations, including the communications control capability of the associated stations.

A BIND configuration logging statement that specifies output methods, format options, and severity levels associated with a category of messages to be logged.

A computed value based on the contents of a packet. The value is sent with the packet when it is transmitted. The receiving host computes a new value based on the received data. If the originating and receiving values are the same, the receiver has a high degree of confidence that the data was received correctly.

A logical (virtual) link that provides a communications connection between adjacent nodes.

An EGP metric. See metric and EGP. Valid values are from 0 to 255 inclusive.

An architecture of standard programming interfaces, conventions, and server functions (for example, naming, distributed file system, remote procedure call) for transparently distributing applications acr oss networks of heterogeneous computers.

A collection of several different data repositories that look like a single database to the user. The Domain Name System (DNS) is a distributed database.

A form of network management in which network managers and management s oftware are dispersed across many systems.

The technology that enables the distribution throughout the network of computing power and storage facilities to user work areas, such as offices, laboratories, or machines on factory floors.

A collection of computer systems, tied together by communications networks for the purpose of sharing resources; end users do not need to be aware of the physical location of the shared resources.

See Domain Name System .

An organizational unit with administrative responsibility for naming networks or hosts. An inter net domain name consists of a sequence of names (labels) separated by periods (dots); for example, tundra.mpk.ca.us.

The name used to refer to a fully qualified domain or subdomain. For example, in cat.food.iams.com , food.iams.com , iams.com , and .com are all domain names. Each name specifies a different domain level.

See dotted-decimal notation .

The syntactic representa tion for a 32-bit integer that consists of four 8-bit numbers written in base 10 with periods (dots) separating them; used to represent IP addresses in the Internet, as in 192.67.67.20. Many Internet application programs accept dotted-decimal notation in place of destination machine names.

Transferring a copy of a system image from a load host to a target. Some systems, such as DEC WANrouter systems and Compaq DECserver terminal servers, automatically request a downline load of their image upon startup and reboot. One of the functions of a TFTP server.

The change in a clock's time rate over a specified period.

A measure, in Hertz per second, of how quickly the skew of a clock is changing. See also skew .

The automatic rerouting of traffic based on a sensing and analysis of current actual network conditions; not including cases of routing decisions taken on predefined information.

A superset of the BOOTP protocol that enables the automatic assignment of IP addresses to clients on networks from a pool of addresses. The IP address assignment and configuration occurs automatically whenever appropriate client systems (workstations and portable computers) attach to a network. The TCP/IP Services for OpenVMS implementation of DHCP is based on the JOIN product by Competitive Automation.

A type of routing where a host or router talks to adjacent routers to learn what networks each router is connected to. Subse quently, the kernel's routing tables are updated when the router learns new information. There are many routing protocols including Interior Gateway Protocols (RIP, OSPF) and Exterior Gateway Protocols (EGP and BGP).

A port number temporarily assigned to a client process for the duration of a session. When the client process terminates, the port number can be assigned to another proces s. The port number is usually from 1024 to 5000.

See Exterior Gateway Protocol .

The classification in Internet standards for optional protocols.

The service whereby a computer user can exchange messages with other computer users (or groups of users) by means of a communications network; one of the most popular uses of the Internet.

See electronic mail .

A technique used by layered protocols in which a layer adds header informatio n to the protocol data unit (PDU) from the layer below. As an example, in Internet terminology, a packet would contain a header from the physical layer, followed by a header from the Network layer (IP), followed by a header from the Transport layer (TCP), followed by the application protocol data.

A process of encoding information so the meaning of its content is no longer immediately obvious to a nyone who obtains a copy of it.

See end system .

A nonrouting system; can receive data packets addressed to it and send data packets to other systems on the same subnet but cannot relay, route, or forward data packets to other systems.

An individual, manageable piece of a network; has attributes that describe it, a name that identifies it, and an interface that supports management operations.

A collection of entities that share the same properties and have the same parent entity; each member of the class has a unique identifier within the class. Entity classes have class names.

An architecturally defined collection of entities. The entities in the group must have a common top entity and must all be of the same class.

A logical hierarchical tree structures of manageable entities in which child entities are below their parent entities. C hildren can be accessed only through their parents' agent.

An attribute that specifically identifies an entity. See also attribute group .

A label associated with some entities used to identify or locate them for management purposes.

A baseband network medium. Commonly used to connect a local area network.

A measurable network-specific or system-specific occurrence for which a logging component maintains a record.

The classification in Internet standards for protocols that are developed as part of an ongoing research project not related to an operational service offering; not intended for operational use.

The Compaq TCP/IP Services for OpenVMS database with directory names that can be mounted from remote NFS clients.

A file in an exported directory or a subdirectory of an exported directory. See also exporting .

A file system that can be accessed by a remote system using the Network File System. The local system imports the remote file system. Both the remote and local system must be configured to grant and receive access to the file system.

Identifying a directory on an NFS server that can be remotely mounted by NFS clients.

A feature of OpenVMS Alpha V ersion 7.2 that allows the use of Windows-style file specifications. This feature provides greater flexibility for OpenVMS Alpha systems to store, manage and access files that have names similar to those in a Windows 95 or Windows NT environment.

Multiple LANs connected with data link relays or bridges.

The protocol that distributes routing information to the gateways that interconnect networks.

A class of routing protocols used to exchange routing information within an autonomous system.

One of a class of exterior gateway protocols.

See Fiber Distributed Data Interface .

The operation of two commands that allow a system manager to fetch a value from a data item or to store a value into a data item.

The high-speed (100 mb/s) networking standard based on fiber optics, established by the American National Standards Institute (ANSI); uses 1300 nanometer light wavelength. FDDI networ ks are limited to approximately 200 km in length, with repeaters every 2 km or less.

A uniquely named collection of information with shared managerial and structural properties.

The characteristic of a file, such as its size or creation date. The values of some file attributes may change d uring the lifetime of a file.

The information that is stored within a file and comprises its contents (as opposed to its attributes).

System-specific information that identifies a file on its storage system.

The host whose principal purpose is to store files and provide network access to them.

System-specific information that identifies a file on its storage system.

A method for recording, cataloging, and accessing files on a volume.

The protocol and software that permit a user on one host to access and transfer files to and from another host over a network. See also Trivial File Transfer Protocol .

The set of rules that govern the organization of the Ope nVMS file system, external to the files themselves.

The utility that provides information about users on local and remote systems.

(1) The function of a receiving entity to limit the amount or rate of data that is sent by a transmitting entity. (2) The control of the rate at which hosts or gateways inject packets into a network or Internet, usually to avoid congestion. Flow control mechanisms can be implemented at various levels and allow communicating layers to match their data transfer and receive rates. Simplistic schemes, like ICMP source quench, simply ask the sender to cease transmission until congestion ends. More complex schemes vary the transmission rate continuously.

The name server that processes recursive requests that a slave server cannot resolve locally; has access to the Internet. See also BIND server , cache server , primary server , secondary server , and slave server .

The table that GATED uses internally to store routing information it learns from routing protocols is a routing table; a lso known as a routing information base, or RIB. The routing table is used to collect and store routes from various protocols.

The table in the kernel that controls the forwarding of packets is a forwarding table, also known as a forwarding information base, or FIB.

See fully qualified domain name .

A piece of a packet that results from a router dividing an IP datagram into smaller pieces for transmission across a network that cannot handle the original datagram size. Fragments use the same format as datagrams; fields in the IP header declare whether a datagram is a fragment and, if so, where the data in the fragment occurred in the original datagram. IP software at the receiving end must reassemble the fragments. See also maximum transmission unit .

The IP process of breaking up packets into smaller packets for transmission; allows a packet originating in a network that allows a large packet size to traverse a network that limits packets to a smaller size. The destination host reassembles the fragments. See also maximum transmissio n unit .

A Data Link layer packet that contains the header and trailer information required by the physical medium.

See File Transfer Protocol .

A circuit designed for transmission in both directions at the same time. Contrast with half-duplex circuit .

Data transmission in both directions at the same time. Contrast with half-duplex transmission .

The full site name of a system, such as scryber.enet.dec.com rather than just the host name of scryber .

A parameter in a $QIO system service call that defines the specific function of that $QIO.

A routing daemon that can be configured to route one or more of the following protocols: RIP, BGP, EGP, and OSPF .

A communications device or program that passes data between networks having similar functions but dissimilar implementations. The term router is now used in place of the original definition of gateway .

An intermediate destination by which packets are delivered to their ultimate destination.

A host address of another router that is directly reachable through an attached ne twork. As with any host address it may be specified symbolically.

Another term for an access system.

See GATED .

See group identification .

One billion bits.

One billion bytes.

The identification code for a group of UNIX users.

A circuit designed for transmission in either direction, but only one direction at one time. Contrast with full-duplex circuit .

Data transmission in either direction, but only one direction at a time. Contrast with full-duplex transmission .

The exchange of connection information between two communicating entities; takes place to enable the successful completion of a connection. Used, for example, in establishing a TCP connection between client and server applications.

The address that identifies the connection device between the network controller of a host and the network cable. See also address .

A mechanism that allows you to assign more than one name to a file. Both the new name and the file being linked must be in the same file system. See also link .

The portion of a packet that precedes the actual data and contains control information such as source and destination address and error checking.

A technique used by PPP and SLIP protocols to reduce the number of bytes per frame when sending packets over a slow serial link. The use of header compression is negotiated between the client and servers processes to reduce the size of the IP and TCP headers.

A network consisting of different network protocols or different operating system software, such as OpenVMS and UNIX.

Routing based on domains. Interdomain routers are responsible only for getting data to the right domain and intradomain routers take responsibility for routing within the domain.

The number of connections between two hosts, based on the number of different routers needed to traverse the distance between the two hosts.

A term used in routing. Number of hosts separating a source and final destination (including the final destination) on a network.

A computer system that acts as a source or destination of network messages sometimes called node .

The IP address of any system. Usually specified in dotted-decimal notation. There are four values in the range from 0 to 255 inclusive, separated by dots (.). For example, 132.236.199.63 or 10.0.0.51. It can also be specified as an 8-digit hexadecimal string preceded by 0x. For example, 0x0a000043. In addition, if the options noresolv statement is n ot specified, this can be a symbolic host name. For example, gated.cornell.edu or nic.ddn.mil . The numeric forms are preferred over the symbolic form.

See host number .

The Compaq TCP/IP Services for OpenVMS database that is created by default; allow s users to use host names; contains host names, IP addresses of the hosts, and any alias names for the hosts.

The name given to a network host. See also fully qualified domain name and alias .

The part of an IP address that identifies which host on the network is bein g addressed.

Also called Transport layer. The second-highest level in the Internet architecture model; provides end-to-end communication services, including mechanisms such as end-to-end reliability and network control. Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) reside in this layer.

See Internet Architecture Board .

The TELNET options that allow TELNET users to connect to hosts that support 3270 terminals.

See Internet Control Message Protocol .

See Interior Gateway Protocol .