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 represented as "monet.Berke-
       ley.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 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 4.10 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
       https://www.kernel.org/doc/man-pages/.



Linux				  2010-11-07			   HOSTNAME(7)