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+.\" Copyright (c) 1986 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms are permitted
+.\" provided that the above copyright notice and this paragraph are
+.\" duplicated in all such forms and that any documentation,
+.\" advertising materials, and other materials related to such
+.\" distribution and use acknowledge that the software was developed
+.\" by the University of California, Berkeley. The name of the
+.\" University may not be used to endorse or promote products derived
+.\" from this software without specific prior written permission.
+.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+.\"
+.\" @(#)resolver.5 5.9 (Berkeley) 12/14/89
+.\" $Id: resolver.5,v 8.4 1997/03/14 02:29:49 vixie Exp $
+.\"
+.Dd November 11, 1993
+.Dt RESOLVER @FORMAT_EXT_U@
+.Os BSD 4
+.Sh NAME
+.Nm resolver
+.Nd resolver configuration file
+.Sh SYNOPSIS
+.Pa /etc/resolv.conf
+.Sh DESCRIPTION
+The
+.Nm resolver
+is a set of routines in the C library
+.Pq Xr resolve @LIB_NETWORK_EXT@
+that provide access to the Internet Domain Name System.
+The
+.Nm resolver
+configuration file contains information that is read
+by the
+.Nm 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
+.Nm resolver
+information.
+.Pp
+On a normally configured system, this file should not be necessary.
+The only name server to be queried will be on the local machine,
+the domain name is determined from the host name,
+and the domain search path is constructed from the domain name.
+.Pp
+The different configuration options are:
+.Bl -tag -width "nameser"
+.It Li nameserver
+Internet address (in dot notation) of a name server that the
+.Nm resolver
+should query. Up to
+.Dv MAXNS
+(currently 3) name servers may be listed, one per keyword.
+If there are multiple servers, the
+.Nm resolver
+library queries them in the order listed.
+If no
+.Li 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).
+.It Li domain
+Local domain name.
+Most queries for names within this domain can use short names
+relative to the local domain.
+If no
+.Li domain
+entry is present, the domain is determined from the local host name returned by
+.Xr gethostname @BSD_SYSCALL_EXT@ ;
+the domain part is taken to be everything after the first
+.Sq \&. .
+Finally, if the host name does not contain a domain part, the root
+domain is assumed.
+.It Li search
+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.
+This may be changed by listing the desired domain search path
+following the
+.Li search
+keyword with spaces or tabs separating the names.
+Most
+.Nm resolver
+queries will be attempted using each component
+of the search path in turn until a match is found.
+Note that this process may be slow and will 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.
+.Pp
+The search list is currently limited to six domains
+with a total of 256 characters.
+.It Li sortlist
+Allows addresses returned by gethostbyname to be sorted.
+A
+.Li 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:
+.Bd -literal -offset indent
+sortlist 130.155.160.0/255.255.240.0 130.155.0.0
+.Ed
+.It Li options
+Allows certain internal
+.Nm resolver
+variables to be modified.
+The syntax is
+.D1 Li options Ar option ...
+where
+.Ar option
+is one of the following:
+.Bl -tag -width "ndots:n "
+.It Li debug
+sets
+.Dv RES_DEBUG
+in
+.Ft _res.options .
+.It Li ndots: Ns Ar n
+sets a threshold for the number of dots which
+must appear in a name given to
+.Fn res_query
+(see
+.Xr resolver @LIB_NETWORK_EXT@ )
+before an
+.Em initial absolute query
+will be made. The default for
+.Ar n
+is
+.Dq 1 ,
+meaning that if there are
+.Em any
+dots in a name, the name will be tried first as an absolute name before any
+.Em search list
+elements are appended to it.
+.El
+.El
+.Pp
+The
+.Li domain
+and
+.Li search
+keywords are mutually exclusive.
+If more than one instance of these keywords is present,
+the last instance wins.
+.Pp
+The
+.Li search
+keyword of a system's
+.Pa resolv.conf
+file can be
+overridden on a per-process basis by setting the environment variable
+.Dq Ev LOCALDOMAIN
+to a space-separated list of search domains.
+.Pp
+The
+.Li options
+keyword of a system's
+.Pa resolv.conf
+file can be amended on a per-process basis by setting the environment variable
+.Dq Ev RES_OPTIONS to a space-separated list of
+.Nm resolver
+options as explained above under
+.Li options .
+.Pp
+The keyword and value must appear on a single line, and the keyword
+(e.g.,
+.Li nameserver )
+must start the line. The value follows the keyword, separated by white space.
+.Sh FILES
+.Pa /etc/resolv.conf
+.Sh SEE ALSO
+.Xr gethostbyname @LIB_NETWORK_EXT@ ,
+.Xr hostname @DESC_EXT@ ,
+.Xr @INDOT@named @SYS_OPS_EXT@ ,
+.Xr resolver @LIB_NETWORK_EXT@ ,
+.Xr resolver @FORMAT_EXT@ .
+.Dq Name Server Operations Guide for Sy BIND
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