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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 subdomain of the Internet would be represented as


       (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   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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