|
daisy chain
A daisy chain is a type of bus topology created by connecting each device to the next device with a separate cable. Node A connects to Node B, Node B to Node C, and so on in a line. In an AppleTalk network, the daisy-chain topology is created using PhoneNet connectors and twisted pair wiring (regular telephone wire). A daisy-chain configuration must be terminated at both ends using terminating resistors.
Data Link Control (DLC)
DLC is a generic term that refers to a protocol, such as Token Ring or Ethernet, used to transfer data across a single physical link.
data service unit (DSU)
A DSU is a device that converts a binary signal from the format used on a LAN to that used by a T1 line. It resolves differences in the way each system represents binary numbers. It sits between a CSU and a T1 MUX, and is usually combined with a CSU in a device called a "CSU/DSU."
datagram
The term "datagram" is another word for a Network Layer packet.
de facto
De facto standards are standards that are not developed by an official standards-making organization, and are usually created by a single vendor or group of vendors. Nevertheless, they are widely accepted and used, usually to allow interoperation with a popular system.
decapsulation
As a data transmission is passed up through the protocol stack of a receiving computer, each protocol layer first removes the header that was added by its peer process on the sending computer, then passes the remaining data to the protocol layer just above. This process is referred to as decapsulation.
decryption
The process of unscrambling encrypted data to restore the original meaningful message is referred to as decryption.
default gateway
A default gateway is a router that provides access to all hosts on remote networks. Typically, a network administrator configures a default gateway for each node on a network.
device driver
A device driver is a program that controls hardware devices attached to a computer, such as a printer or hard disk drive.
digital
A digital signal is transmitted as a pattern of binary bits. Information is represented as a series of 1s and 0s, high or low electrical voltages, or the absence or presence of light.
digital access cross-connect switch (DACS)
A DACS is a connection system that establishes semipermanent (not switched) paths for voice or data signals. All physical wires are attached to the DACS once, then electronic connections between them are made by entering instructions.
Digital Subscriber Line (DSL)
DSL is a modem technology that converts existing twisted pair telephone lines into high-speed data lines that can also carry separate telephone communications. Variants of DSL include ADSL, RADSL, ADSL Lite, IDSL, and VDSL.
Domain Name System (DNS)
DNS is the online distributed database system that maps human-readable computer names to IP addresses.
duplex
The process of transmitting data in two directions is referred to as duplex transmission. There are three modes of transmission: simplex, half-duplex, and full-duplex. In simplex transmission, a signal can only be transmitted in one direction. In half-duplex transmission, the signal can travel in both directions, but not simultaneously. Full-duplex transmission allows signals to travel in both directions simultaneously.
|