Index for Section 4

Alphabetical listing for R

Bottom of page

resolv.conf(4)
NAME
  resolv.conf - Resolver configuration file

SYNOPSIS
  /etc/resolv.conf

DESCRIPTION
  The resolver is a set of routines in the C library (resolver(4)) that
  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.

  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. For example:

       keyword value

  The file format is as follows:

       nameserver Address

  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 DomainName

  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 Domain_Name1 DomainName2 ...

  Search list for host-name lookup.  Up to six domains (separated by spaces
  or tabs) with a total of 256 characters can be specified.  If no search
  entry is present, the search list consists of the local domain name.

  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.

  You can also specify a search list on a per-process basis by specifying the
  LOCALDOMAIN environment variable. See resolver(4).

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

       options allow_special all | { \char }

  Option for defining valid characters in hostnames.  Specify all to disable
  hostname checking (allow all characters) or define a set of valid
  characters by using the { \char } syntax, where char is the character you
  want to allow.  For example, you can allow the semicolon, underscore, and
  colon characters by using { \; \_ \: }.

  Disabling hostname checking altogether is not recommended.  By default, the
  allow_special option is not set and strict hostname checking is enforced.

       options ndots:n

  Option for hostname lookup.  The n specifies the minimum number of dots a
  name must contain in order for resolver to look up the name as given.	 If
  the lookup fails, the search list (if specified) is applied. The range for
  n is from 0 to 15.  If no options entry is present, the minimum number of
  dots is 1.

  You can also specify the number of dots on a per-process basis by using the
  RES_OPTIONS environment variable. See resolver(4).

CAUTIONS
  Any white space entered after the domain name is not ignored but is
  interpreted as part of the domain name.

SEE ALSO
  Commands: named(8)

  Functions: gethostbyname(3), resolver(4)

  Files: hostname(5)

Index for Section 4

Alphabetical listing for R

Top of page