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Command: resolver | Section: 5 | Source: 4.4BSD | File: resolver.5
RESOLVER(5) FreeBSD File Formats Manual RESOLVER(5)
NAME
resolver - resolver configuration file
SYNOPSIS
resolv.conf
DESCRIPTION
The 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.
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.
The different configuration options are:
nameserver 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).
domain 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(2); the domain part
is taken to be everything after the first `.'. Finally, if
the host name does not contain a domain part, the root domain
is assumed.
search Search list for host-name lookup. The search list is
normally determined from the local domain name; by default,
it begins with the local domain name, then successive parent
domains that have at least two components in their names.
This may be changed by listing 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. 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.
The search list is currently limited to six domains with a
total of 256 characters.
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 (e.g.
nameserver) must start the line. The value follows the keyword,
separated by white space.
FILES
/etc/resolv.conf The file resolv.conf resides in /etc.
SEE ALSO
gethostbyname(3), resolver(3), hostname(7), named(8)
Name Server Operations Guide for BIND.
HISTORY
The resolv.conf file format appeared in 4.3BSD.
BSD 4 May 10, 1991 BSD 4