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HOSTNAME(7)                         BSD Miscellaneous Information Manual                         HOSTNAME(7)

NAME
     hostname -- host name resolution description

DESCRIPTION
     Hostnames are domains, where a domain is a hierarchical, dot-separated list of subdomains; for example,
     the machine monet, in the Berkeley subdomain of the EDU subdomain of the Internet would be represented
     as

           monet.Berkeley.EDU

     (with no trailing dot).

     Hostnames are often used with network client and server programs, which must generally translate the
     name to an address for use.  (This function is generally performed by the library routine
     gethostbyname(3).)  Hostnames are resolved by the Internet name resolver in the following fashion.

     If the name consists of a single component, i.e., contains no dot, and if the environment variable
     ``HOSTALIASES'' is set to the name of a file, that file is searched for any string matching the input
     hostname.  The file should consist of lines made up of two white-space separated strings, the first of
     which is the hostname alias, and the second of which is the complete hostname to be substituted for
     that alias.  If a case-insensitive match is found between the hostname to be resolved and the first
     field of a line in the file, the substituted name is looked up with no further processing.

     If the input name ends with a trailing dot, the trailing dot is removed, and the remaining name is
     looked up with no further processing.

     If the input name does not end with a trailing dot, it is looked up by searching through a list of
     domains until a match is found.  The default search list includes first the local domain, then its par-ent parent
     ent domains with at least 2 name components (longest first).  For example, in the domain CS.Berke-ley.EDU, CS.Berkeley.EDU,
     ley.EDU, the name lithium.CChem will be checked first as lithium.CChem.CS.Berkeley.EDU and then as
     lithium.CChem.Berkeley.EDU.  Lithium.CChem.EDU will not be tried, as there is only one component
     remaining from the local domain.  The search path can be changed from the default by a system-wide con-figuration configuration
     figuration file (see resolver(5)).

SEE ALSO
     gethostbyname(3), resolver(5), mailaddr(7), named(8)

HISTORY
     Hostname appeared in 4.2BSD.

BSD                                           December 30, 1993                                          BSD