daemon. A UNIX system service. It is a program that is active in the background but not connected to a terminal.
datagram. A message sent in a packet-switched computer communications network. The message made up of source and destination addresses and the data itself. The datagram model implies that no connection, such as a virtual circuit, is needed to send them and that they are not required to be delivered reliably or in sequence.
Data Communication Equipment (DCE). Connects with a DTE or DCE driving the complementary signals (for example, modems). For a DTE/DTE communication, a null modem must be used to make one of the DTEs appear as a DCE.
Data Terminal Equipment (DTE). (Connects with a DTE or DCE driving the complementary signals (for example, computers, terminals, printers). For a DTE/DTE communication, a null modem must be used to make one of the DTEs appear as a DCE.
DCD. Data Carrier Detect.
DCE. See Data Communication Equipment.
DTE. See Data Terminal Equipment.
DTR. Data Terminal Ready.
destination address. The network and host identifiers.
dotted decimal notation. A method of representing the 32 bits of an Internet address as four 8-bit numbers written as base 10 numbers separated with dots. For example, the hex number 1A2B34FF would be written as 188.8.131.52 .