Data Encryption Key (DEK)

Much like an actual key used for locking and re-opening doors, DEKs are used for the encryption and decoding of message text, sometimes in the form of a digital signature.

Data Encryption Standard (DES)

A standardised encryption method widely used on the Internet.

Datagram

A block of data that is 'smart' enough (actually, which carries enough information) to travel from one Internet site to another without having to rely on earlier exchanges between the source and destination computers.

DECnet

The propriety network protocol designed by Digital Equipment Corporation.

Dedicated Line

A communications line that is used solely for computer connections. If you buy an additional phone line for your modem, that's a dedicated line. There are other types of dedicated lines (such as T3s and T1s) that are used for larger network entities.

Dial-Up

A widely used method of accessing the Internet. A dial-up connection uses regular phone lines to connect one computer to another via modem.

 

DNS

See Domain Name System

Domain

A 'logical' region of the Internet. People sometimes refer to them loosely as 'sites'. Generally, a domain corresponds to an IP address or an area on a host.

Domain Name System (DNS)

The DNS is a static, hierarchical name service used with TCP/IP hosts, and is housed on a number of servers on the  Internet. Basically, it maintains a database for figuring out and finding (or resolving) host names and IP addresses on the Internet. This allows users to specify remote computers by host names rather than numerical IP addresses (if you've used UNIX, you may have heard the DNS referred to as the BSD UNIX BIND service).