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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 "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
       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 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


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


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