Database Server:-

Any database application that follows the client/server architecture model, which divides the application into two parts: a front-end running on the user's workstation and a back-end running on a server or host computer. The front end interacts with the user and collects and displays the data. The back-end performs all the computer-intensive tasks, including data analysis, storage, and manipulation.

Data Encryption Standard:-

Abbreviated DES. A standard method of encrypting and decrypting data, developed by the United States National Bureau of Standards. DES works by a combination of transposition and substitution. It is used by the federal government and most banks and money-transfer systems to protect all sensitive computer information. DES has remained Unbroken despite years of use. This method completely randomizes the information so that it is impossible to determine the encryption key even if some of the original text is known.

Data-link Layer:-

The second of seven layers of the ISC/OSI model for computer-to-computer communications.. The data-link layer validates the integrity of the flow of data from one node to another by synchronizing blocks of data and controlling the flow of data.

The Institute of Electrical and Electronic Engineers (IEEE) has divided the data-link layer into two other layers; the logical link control (LLC) layer sits above the media access control (MAC) layer.

Data Packet:-

One unit of information transmitted as a discrete entity from one node on the network to another. More specifically, in packet-switching networks, a packet is a transmission unit of a fixed maximum length that contains a header, a set of data, and error control information.

Data-transfer Rate:-

1. The speed at which a disk drive can transfer information from the drive to the processor, usually measured in megabits or megabytes per second. For example, an SCSI (Small computer System Interface) drive can reach a transfer rate of up to 20 megabytes per second.

2. The rate of information exchange between two systems For example, a PC modem may achieve 14,400 bits per second (bps) or 28,800 bps; and Ethernet local-area network (LAN) may achieve 10 megabits per second (mbps); and a Fiber Distributed Data Interface (FDDI) system may reach 100 mbps.

DB connector:-

Any of several types of cable connectors used for parallel or serial cables. The number following the letters DB (for data bus) indicates the number of pins that the connector usually has; a DB-25 connector can have up to twenty-five pins, and a DB-9 connector can have up to nine. In practice, not all the pins (and not all the lines in the cable may be present in the large connectors. If your situation demands that all the lines be present make sure you buy the right cable. Common DB connectors include the following:

• DB-9 , defined by the RS-449 standard as well as the ISO (International Standards Organization).

• DB-25 , a standard connector used with RS-232-C wiring, with twenty-five pins (thirteen on the top row and twelve on the bottom).

• DB-37 , defined as the RS-449 primary channel connector. DB-15, DB-19, and DB-50 connectors are also available. The accompanying illustration shows a male and female DB-25 connector.

Decibel:-

Abbreviated dB. One tenth of a bel, a unit of measurement common in electronics that quantifies the loudness or strength of a signal. A decibel is a relative measurement derived by comparing a measured against a known reference.

Dedicated Server:-

A computer on the network that functions only as a server performing specific network tasks, such as storing files, printing, or managing external communications.

Delimiter:-

1. Any special character that separates individual items in a data set or file. For example, in a comma-delimited file, the comma is placed between each data value as the delimiter.

2. In a Token Ring network, a delimiter is a bit pattern that defines the limits of a frame or token on the network.

Device Driver:-

A small program that allows a computer to communicate with and control a device. Each operating system contains a standard set of device drivers for the keyboard, the monitor, and so on. What you add, specialized peripheral devices, such as a CD-ROM disk drive or a network interface card; you must install the appropriate device driver so that the operating system knows how to manage the device.

Digital Equipment Corporation:-

Abbreviated DEC. A major manufacturer of minicomputers and mainframe computers, founded in 1957, long recognized for its high-quality computer systems. DEC's most popular product line, the VAX series, ranges form small desktop systems to large mainframes suitable for scientific and commercial processing.

DIN connector:-

A connector that meets the specification of the German national standards body, Deutsche Industries Norm (DIN). Several models of Macintosh computer use 8-pin DIN connectors as the serial port connector. On many IBM-compatible computers, a 5-pin DIN connector connects the keyboard to the system unit.

DIP Switch:-

A small switch used to select the operating mode of a device, mounted as a dual in-line package. DIP switches can be either sliding or rocker switches, or they are often ground together for convenience; see the accompanying illustration. They are used in printed circuit boards, dot-matrix printers, modems, and many other peripheral devices.

Disable Login:-

A Novell Net Ware server utility used to prevent users from logging in to the file server, usually executed before maintenance is performed on the server. To allow users to log in again when the maintenance is complete, use ENABLE LOGIN.

DiskSet:-

A Novell NetWare server utility that adds identification and configuration information for a new hard disk to a host bus adapter's EEPROM (electrically erasable programmable read-only memory) chip. DISKSET is used when a new disk subsystem is installed or when a hard disk is replaced on the server.

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