X.25

A packet-switching network standard developed by the International Telegraph and Telephone Consultative Committee (CCITT), which has been renamed the International Telecommunications Union (ITU). The standard, referred to as Recommendation X.25, was introduced in 1974 and is now implemented most commonly in WANs.

X.400

An International Telecommunications Union (ITU) standard for message exchange.

X.500

An International Telecommunications Union (ITU) standard for directory services.

X.500 Recommendations

A set of industry-accepted guidelines that define how a network directory should be defined.

XCOPY

Copies files (except hidden and system files) and directory trees.

XMS

The Extended Memory Specification developed by Microsoft to allow DOS programs to use extended memory. This is provided in DOS 5 & 6 by HIMEM.SYS.

.Z

Filename extension that identifies a Unix file compressed by the gzip or the compact utility.

ZAK

See Zero Administration Kit.

ZAP Files

Files that can be used with Windows Installer packages instead of Microsoft Installer (MIS) format files. ZAP files are used to install applications using their native Setup program. See also Windows Installer Packages and Microsoft Installer (MSI).

ZAW

See Zero Administration for Windows.

Z.E.N.works

See Novell Z.E.N.works.

Zero Administration for Windows (ZAW)

A Microsoft-led initiative designed to lower the total cost of ownership of Windows-based network clients in the corporate world. See also NetPC, Network Computer, Thin Client, and Total Cost of Ownership.

Zero Administration Kit (ZAK)

A collection of tools, scripts, and methodologies used by system administrators to simplify the implementation of security management on the Windows family of operating systems.

Zero Insertion Force Socket

A specially designed chip socket that makes replacing a chip easier and safer. To change a chip in a ZIF socket, you raise a lever beside the socket to free the original chip’s pins from the socket. You then slide the old chip out and slide in the replacement chip, taking care to align the pins and holes. Finally, you lower the lever again. A ZIF socket minimizes damage to the delicate pins that connect the chip to the rest of the system.

Zero Slot LAN

A local area network that uses one of the existing serial or parallel ports on the computer rather than a special network interface card plugged in to the computer’s expansion bus. See also Peer-to-Peer Network.

Zero-Wait-State Computer

A computer that can process information without processor wait states, which are clock cycles during which no instructions are executed because the processor is waiting for data from a device or from memory. See also Wait State.

ZIF Socket

See Zero Insertion Force Socket.

ZIP

See Zone Information Protocol.

.ZIP

Filename extension that identifies a file compressed by the PKZIP or WinZip utilities. See also PKZIP, WinZip, and ZIP File.

ZIP File

A file whose contents have been compressed by one of the popular file-compressing utilities, such as PKZIP, WinZip, or other comparable program; the filename extension is .ZIP. See also File Compression, PKZIP, WinZip, and .ZIP.

ZIP Storm

A broadcast storm occurring when a router running AppleTalk reproduces or transmits a route for which there is no corresponding zone name at the time of execution. The route is then forwarded by other routers downstream, thus causing a ZIP storm. See also Broadcast Storm and Zone Information Protocol.

Zone

1. An AppleTalk version of a workgroup. Multiple network segments can be joined to form a single zone, and a single segment can have multiple zones.
2. Subtree of the DNS database that is considered a single unit.

Zone Information Protocol (ZIP)

A Session-layer protocol used by AppleTalk to map network numbers to zone names. NBP uses ZIP in the determination of networks containing nodes that belong to a zone. See also ZIP Storm and Zone.

Zone Transfer

Copies information from a primary DNS server to a secondary DNS server.

Zoo

A collection of viruses used for testing by researchers. See also In The Wild and Zoo Virus.

Zoo Virus

A zoo virus exists in the collections of researchers and has never infected a real world computer system. See also In The Wild.