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 domain would be  rep‐
       resented as "monet.Berkeley.EDU".

       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  environ‐
       ment  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  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.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 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2010-11-07                                HOSTNAME(7)