unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (SunOS-5.10)
Page:
Section:
Apropos / Subsearch:
optional field

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



NAME
       resolv.conf - resolver configuration file

SYNOPSIS
       /etc/resolv.conf

DESCRIPTION
       The  resolver  is a set of routines that provide access to the Internet
       Domain Name System. See resolver(3RESOLV). resolv.conf is a  configura-
       tion  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 val-
       ues 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 <&lt;resolv.h>&gt;.  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 algorithm  to  try  a  name
                               server until the query times out. It then tries
                               the the name servers that  follow,  until  each
                               query  times  out.  It  repeats  all  the  name
                               servers until a maximum number of  retries  are
                               made.



       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  deter-
                               mined  from sysinfo(2) or from gethostname(3C).
                               (Everything after the first `.' is presumed  to
                               be  the domain name.) If the host name does not
                               contain a  domain  part,  the  root  domain  is
                               assumed.  You  can use the LOCALDOMAIN environ-
                               ment 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 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.  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:


                               sortlist 130.155.160.0/255.255.240.0 130.155.0.0



       options                 Allows  certain  internal resolver variables to
                               be modified. The syntax 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     performed.     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
                               retrans:n

                                   Sets the amount of time the  resolver  will
                                   wait  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
                                   <&lt;resolv.h>&gt;.  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
                               retry:n

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




                               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 hav-
                                   ing all clients try the first listed server
                                   first every time.



                               no-check-names

                                   Sets  RES_NOCHECKNAME in _res.options. This
                                   disables the modern BIND checking of incom-
                                   ing  host  names and mail names for invalid
                                   characters such  as  underscore  (_),  non-
                                   ASCII, or control characters.



                               inet6

                                   Sets  RES_USE_INET6 in _res.options. In the
                                   Solaris BIND port, this has  no  effect  on
                                   gethostbyname(3NSL).   To   retrieve   IPv6
                                   addresses or  IPv4  addresses,  use  getad-
                                   drinfo(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  prece-
       dence.

       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 domains.

       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 options.

       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.

FILES
       /etc/resolv.conf



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


       tab()     allbox;     cw(2.750000i)|    cw(2.750000i)    lw(2.750000i)|
       lw(2.750000i).  ATTRIBUTE TYPEATTRIBUTE VALUE Interface  StabilityStan-
       dard BIND 8.3.3


SEE ALSO
       domainname(1M),  sysinfo(2), gethostbyname(3NSL), getnameinfo(3SOCKET),
       getipnodebyname(3SOCKET),      gethostname(3C),      resolver(3RESOLV),
       attributes(5)

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



SunOS 5.10                        15 Dec 2004                   resolv.conf(4)