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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 gethostby-
       name(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  further  process-
       ing.

       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 components (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.Berke-
       ley.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 3.05 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)