


RESOLVER(5)                                           RESOLVER(5)


NNAAMMEE
       resolver - resolver configuration file

SSYYNNOOPPSSIISS
       /etc/resolv.conf

DDEESSCCRRIIPPTTIIOONN
       The  _r_e_s_o_l_v_e_r  is  a  set  of  routines  in  the C library
       (_r_e_s_o_l_v(3)) 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  key-
       words  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:

       nnaammeesseerrvveerr
              Internet address (in dot notation) of a name server
              that  the resolver should query.  Up to MAXNS (cur-
              rently 3) name servers may be listed, one per  key-
              word.   If there are multiple servers, the resolver
              library queries them in the order  listed.   If  no
              nnaammeesseerrvveerr  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).

       ddoommaaiinn Local domain name.  Most queries for  names  within
              this  domain  can  use  short names relative to the
              local domain.  If no ddoommaaiinn entry is  present,  the
              domain  is  determined  from  the  local  host name
              returned by  _g_e_t_h_o_s_t_n_a_m_e(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.

       sseeaarrcchh 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  _s_e_a_r_c_h  keyword with spaces or tabs separating
              the names.  Most resolver queries will be attempted



                        December 14, 1989                       1





RESOLVER(5)                                           RESOLVER(5)


              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 _d_o_m_a_i_n and _s_e_a_r_c_h 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. nnaammeesseerrvveerr) must start  the  line.   The
       value follows the keyword, separated by white space.

FFIILLEESS
       _/_e_t_c_/_r_e_s_o_l_v_._c_o_n_f

SSEEEE AALLSSOO
       gethostbyname(3N), resolver(3), hostname(7), named(8)
       Name Server Operations Guide for BIND

































                        December 14, 1989                       2


