Domain name system

On the Internet, the Domain Name System (DNS) associates various sorts of information with so-called domain names; most importantly, it serves as the "phone book" for the Internet by translating human-readable computer hostnames, e.g. en.wikipedia.org, into the IP addresses, e.g. 66.230.200.100, that networking equipment needs for delivering information. It also stores other information such as the list of mail exchange servers that accept email for a given domain. In providing a worldwide keyword-based redirection service, the Domain Name System is an essential component of contemporary Internet use.
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The online distributed database system that (a) is used to map human-readable addresses into Internet Protocol (IP) addresses, (b) has servers throughout the Internet to implement hierarchical addressing that allows a site administrator to assign machine names and addresses, (c) supports separate mappings between mail destinations and IP addresses, and (d) uses domain names that (i) consist of a sequence of names, i.e., labels, separated by periods, i.e., dots, (ii) usually are used to name Internet host computers uniquely, (iii) are hierarchical, and (iv) are processed from right to left, such as the host nic.ddn.mil has a name (nic -- the Network Information Center), a subdomain (ddn -- the Defense Data Network), and a primary domain (mil -- the MILNET).

<networking> (DNS) A general-purpose distributed, replicated, data query service chiefly used on Internet for translating hostnames into Internet addresses. Also, the style of hostname used on the Internet, though such a name is properly called a fully qualified domain name. DNS can be configured to use a sequence of name servers, based on the domains in the name being looked for, until a match is found.
The name resolution client (e.g. Unix's gethostbyname() library function) can be configured to search for host information in the following order: first in the local /etc/hosts file, second in NIS and third in DNS. This sequencing of Naming Services is sometimes called "name service switching". Under Solaris is configured in the file /etc/nsswitch.conf.
DNS can be queried interactively using the command nslookup. It is defined in STD 13, RFC 1034, RFC 1035, RFC 1591.
BIND is a common DNS server.
Info from Virtual Office, Inc..
(2001-05-14)

DNS