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resolv.conf(4)				   File Formats 			   resolv.conf(4)

       resolv.conf - resolver configuration file


       The  resolver is a set of routines that provide access to the Internet Domain Name System.
       See resolver(3RESOLV). resolv.conf is a configuration file that contains  the  information
       that  is  read  by the resolver routines the first time they are invoked by a process. The
       file is designed to be human readable and contains a list of  keywords  with  values  that
       provide various types of resolver information.

       The resolv.conf file contains the following configuration directives:

       nameserver	      Specifies  the  IPv4 or IPv6 Internet address of a name server that
			      the resolver is to query. Up to MAXNS name servers may  be  listed,
			      one per keyword. See <resolv.h>. If there are multiple servers, the
			      resolver library queries them in	the  order  listed.  If  no  name
			      server  entries  are present, the resolver library queries the name
			      server on the local machine. The resolver library follows the algo-
			      rithm to try a name server until the query times out. It then tries
			      the name servers that  follow,  until  each  query  times  out.  It
			      repeats  all the name servers until a maximum number of retries are

       domain		      Specifies the 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  sysinfo(2)
			      or  from	gethostname(3C).  (Everything after the first `.' is pre-
			      sumed to be the domain name.) If the host name does not  contain	a
			      domain  part,  the root domain is assumed. You can use the LOCALDO-
			      MAIN environment variable to override the domain name.

       search		      The search list for host name lookup. The search list  is  normally
			      determined from the local domain name. By default, it contains only
			      the local domain name. You can change the default behavior by list-
			      ing  the	desired  domain search path following the search keyword,
			      with spaces or tabs separating the  names.  Most	resolver  queries
			      will  be	attempted using each component of the search path in turn
			      until a match is found. This process may be slow and will  generate
			      a  lot of network traffic if the servers for the listed domains are
			      not local. Queries will time out if no server is available for  one
			      of the domains.

			      The  search list is currently limited to six domains and a total of
			      256 characters.

       sortlistaddresslist    Allows addresses returned by the libresolv-internal gethostbyname()
			      to  be sorted. A sortlist is specified by IP address netmask pairs.
			      The netmask is optional and defaults to the natural netmask of  the
			      net.  The  IP  address  and optional network pairs are separated by
			      slashes. Up to 10 pairs may be specified. For example:


       options		      Allows certain internal resolver variables to be modified. The syn-
			      tax is

				options option ...

			      where option is one of the following:

			      debug		Sets RES_DEBUG in the _res.options field.

			      ndots:n		Sets  a  threshold  floor  for the number of dots
						which must appear in a name given to  res_query()
						before	an initial absolute (as-is) query is per-
						formed. See resolver(3RESOLV). The default  value
						for  n	is  1,	which means that if there are any
						dots in a name, the name is  tried  first  as  an
						absolute name before any search list elements are
						appended to it.

			      timeout:n 	Sets the amount of time the  resolver  will  wait
			      retrans:n 	for  a	response from a remote name server before
						retrying the query by means of a  different  name
						server.  Measured  in  seconds,  the  default  is
						RES_TIMEOUT.  See  <resolv.h>.	The  timeout  and
						retrans  values  are  the  starting  point for an
						exponential back off procedure where the  timeout
						is doubled for every retransmit attempt.

			      attempts:n	Sets the number of times the resolver will send a
			      retry:n		query to its name servers before  giving  up  and
						returning  an  error  to the calling application.
						The default is RES_DFLRETRY. See <resolv.h>.

			      rotate		Sets RES_ROTATE in _res.options. The name servers
						are  queried round-robin from among those listed.
						The  query  load  is  spread  among  all   listed
						servers,  rather  than having all clients try the
						first listed server first every time.

			      no-check-names	Sets RES_NOCHECKNAME in _res.options.  This  dis-
						ables  the  modern BIND checking of incoming host
						names and mail names for invalid characters  such
						as  underscore (_), non-ASCII, or control charac-

			      inet6		Sets  RES_USE_INET6  in  _res.options.	 In   the
						Solaris BIND port, this has no effect on gethost-
						byname(3NSL). To retrieve IPv6 addresses or  IPv4
						addresses,  use  getaddrinfo(3SOCKET)  instead of
						setting inet6.

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

       You  can override the search keyword of the system resolv.conf file on a per-process basis
       by setting the environment variable  LOCALDOMAIN  to  a	space-separated  list  of  search

       You can amend the options keyword of the system resolv.conf file on a per-process basis by
       setting the environment	variable  RES_OPTIONS  to  a  space-separated  list  of  resolver

       The  keyword  and value must appear on a single line. Start the line with the keyword, for
       example, nameserver, followed by the value, separated by white space.


       See attributes(5) for descriptions of the following attributes:

       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       |Interface Stability	     |Standard BIND 8.3.3	   |

       domainname(1M),	sysinfo(2),   gethostbyname(3NSL),   getnameinfo(3SOCKET),   getipnodeby-
       name(3SOCKET), gethostname(3C), resolver(3RESOLV), attributes(5)

       Vixie,  Paul,  Dunlap, Keven J., Karels, Michael J. Name Server Operations Guide for BIND.
       Internet Software Consortium, 1996.

SunOS 5.11				   15 Dec 2004				   resolv.conf(4)
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