HOSTNAME(7)                                         Linux Programmer's Manual                                        HOSTNAME(7)



NAME
       hostname - hostname 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  task is generally performed by either getaddrinfo(3) or the obsolete gethostbyname(3).)  Hostnames are
       resolved by the Internet name resolver in the following fashion.

       If the name consists of a single component, that is, 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 fur-
       ther 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 parent domains with at least 2  name  compo-
       nents  (longest  first).   For  example,  in  the domain CS.Berkeley.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
       configuration file (see resolver(5)).

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

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      2008-06-11                                                HOSTNAME(7)