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       hostname - hostname resolution 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

       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  further

       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)).


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


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