DNS (Domain Name System) Server -- DNS is a TCP/IP service that lets you specify a symbolic name instead of an IP address. A symbolic name consists of a user name and a domain name in the format username@domain name. The user name corresponds to the host number in the IP address. The domain name corresponds to the network number in the IP address. A symbolic name might be steve@crocker.com or joanne@cal.edu. The domain identifier is the last part of the domain name, and identifies the type of organization to which the host belongs.

Through DNS, you Internet Service Provider can maintain a database of network numbers and corresponding domain names. When you use a symbolic name, the DNS translates the domain name into an IP address, and sends it over the network. When your Internet Service Provider receives the message, it uses its own database to look up the user name corresponding to the host number.