resolver(4)						     Kernel Interfaces Manual						       resolver(4)

NAME

       resolver - resolver configuration file

SYNOPSIS

       /etc/resolv.conf

DESCRIPTION

       The resolver is a set of routines in the C library that provide access to the Internet Domain Name System.  The resolver configuration file
       (resolv.conf) contains information that is read by the resolver routines the first time they are invoked by a process. The file is designed
       to be read by humans and contains a list of keywords with values that provide various types of resolver information.

       The  different  configuration  options are: Internet address (in dot notation) of a name server that the resolver should query. Up to MAXNS
       (currently 3) name servers may be listed, one per keyword. If there are multiple servers, the resolver library queries them  in	the  order
       listed.	If no nameserver entries are present, the default is to use the name server on the local machine.  (The algorithm used is to try a
       name server, and if the query times out, try the next, until out of name servers, then repeat trying all the name servers until	a  maximum
       number  of  retries  are  made).   Local  domain  name. Most queries for names within this domain can use short names relative to the local
       domain. If no domain entry is present, the domain is determined from the local host name returned by  gethostname();  the  domain  part	is
       taken  to  be  everything  after  the  first dot (.). Finally, if the host name does not contain a domain part, the root domain is assumed.
       Search list for host name lookup. By default, the search list consists of the local domain name.  You can change this system wide by speci-
       fying  search  keyword followed by a list of domain names separated by spaces or tabs, or on a per-process basis by specifying the LOCALDO-
       MAIN environment variable followed by a list of domain names separated by spaces or tabs.

	      Most resolver queries will be attempted using each component of the search path in turn until a match is found.  This process  might
	      be  slow	and generate a lot of network traffic, if the servers for the listed domains are not local, and that queries will time out
	      if no server is available for one of the domains.

	      The search list is currently limited to six domains with a total of 256 characters.  Enables the sorting of  addresses  returned	by
	      gethostname.   A	sortlist comprises pairs of IP addresses and optional netmasks; each IP address and optional netmask are separated
	      by a slash character (/).  The netmask is optional, and defaults to the current network netmask.	You can specify up  to	10  pairs.
	      For  example:  sortlist  130.155.160.0/255.255.240.0 130.155.0.0 Option for host name lookup.  By default, when a host name contains
	      one or more dots (.), resolver looks up the name as given before applying the search list.  The n specifies the  minimum	number	of
	      dots a name must contain in order to be looked up as given before applying the search list.  The range is from 0 to 15.

	      You  can change the resolver options system wide by specifying options keyword followed a list of resolver options separated by spa-
	      ces, or on a per-process basis by specifying the RES_OPTIONS environment variable followed by a list of resolver	options  separated
	      by spaces.

       The  domain  and  search  keywords  are mutually exclusive.  If more than one instance of these keywords is present, the last instance will
       override.

       The keyword and value must appear on a single line, and the keyword (for example, nameserver) must start the line.  The value  follows  the
       keyword, separated by white space.

FILES

       /etc/resolv.conf

RELATED INFORMATION

       Functions: dn_comp(3), dn_expand(3), gethostbyname(3), res_init(3), res_mkquery(3), res_query(3), res_search(3), res_send(3).

       Files: hostname(5).

       Commands: named(8).  delim off

																       resolver(4)