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diff --git a/share/man/man5/resolver.5 b/share/man/man5/resolver.5 new file mode 100644 index 0000000..4116f23 --- /dev/null +++ b/share/man/man5/resolver.5 @@ -0,0 +1,217 @@ +.\" Copyright (c) 1986, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)resolver.5 8.1 (Berkeley) 6/5/93 +.\" $FreeBSD$ +.\" +.Dd December 25, 2013 +.Dt RESOLVER 5 +.Os +.Sh NAME +.Nm resolver +.Nd resolver configuration file +.Sh SYNOPSIS +.Nm resolv.conf +.Sh DESCRIPTION +The +.Xr resolver 3 +is a set of routines in the C library +which provide access to the Internet Domain Name System. +The resolver configuration file contains 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. +.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 nameserver +.It Sy nameserver +Internet address (in dot notation) of a name server +that the resolver should query. +Up to +.Dv 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 +.Sy 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 Sy domain +Local domain name. +Most queries for names within this domain can use short names +relative to the local domain. +If no +.Sy domain +entry is present, the domain is determined +from the local host name returned by +.Xr gethostname 3 ; +the domain part is taken to be everything after the first +.Ql \&. . +Finally, if the host name does not contain a domain part, the root +domain is assumed. +.It Sy 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 +.Sy 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. +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 Sy sortlist +Sortlist allows addresses returned by 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. +E.g., +.Pp +.Dl "sortlist 130.155.160.0/255.255.240.0 130.155.0.0" +.It Sy options +Options allows certain internal resolver variables to be modified. +The syntax is +.Pp +\fBoptions\fP \fIoption\fP \fI...\fP +.Pp +where +.Sy option +is one of the following: +.Bl -tag -width no_tld_query +.It Sy debug +sets +.Dv RES_DEBUG +in _res.options. +.It Sy 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 3 ) +before an +.Em initial absolute query +will be made. +The default for +.Em n +is +.Dq 1 , +meaning that if there are 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. +.It Sy timeout: Ns Ar n +sets the initial amount of time the resolver will wait +for a response from a remote +name server before retrying the query via a different name server. +The resolver may wait longer during subsequent retries +of the current query since an exponential back-off is applied to +the timeout value. +Measured in seconds, the default is +.Dv RES_TIMEOUT , +the allowed maximum is +.Dv RES_MAXRETRANS +(see +.In resolv.h ) . +.It Sy attempts: Ns Ar n +sets the number of times the resolver will send a query to each of +its name servers +before giving up and returning an error to the calling application. +The default is +.Dv RES_DFLRETRY , +the allowed maximum is +.Dv RES_MAXRETRY +(see +.In resolv.h ) . +.It Sy no_tld_query +tells the resolver not to attempt to resolve a top level domain name, that +is, a name that contains no dots. +Use of this option does not prevent +the resolver from obeying the standard +.Sy domain +and +.Sy search +rules with the given name. +.El +.Pp +Options may also be specified as a space or tab separated list using the +.Dv RES_OPTIONS +environment variable. +.El +.Pp +The +.Sy domain +and +.Sy search +keywords are mutually exclusive. +If more than one instance of these keywords is present, +the last instance will override. +.Pp +The keyword and value must appear on a single line, and the keyword +(e.g.\& +.Sy nameserver ) +must start the line. +The value follows the keyword, separated by white space. +.Sh FILES +.Bl -tag -width /etc/resolv.conf -compact +.It Pa /etc/resolv.conf +The file +.Nm resolv.conf +resides in +.Pa /etc . +.El +.Sh SEE ALSO +.Xr gethostbyname 3 , +.Xr resolver 3 , +.Xr hostname 7 +.Rs +.%T "Name Server Operations Guide for BIND" +.Re +.Sh HISTORY +The +.Nm resolv.conf +file format appeared in +.Bx 4.3 . |
