The Free On-line Dictionary of Computing (30 December 2018):

Domain Name System
name service switching

    (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 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.
   (http://virtual.office.com/domains.html).

   (2001-05-14)