4.4BSD/usr/share/man/cat5/resolver.0

RESOLVER(5)                 BSD Programmer's Manual                RESOLVER(5)

NNAAMMEE
     rreessoollvveerr - resolver configuration file

SSYYNNOOPPSSIISS
     rreessoollvv..ccoonnff

DDEESSCCRRIIPPTTIIOONN
     The resolver(3) is a set of routines in the C library which provide ac-
     cess 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 con-
     structed 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 (currently 3) name
                 servers may be listed, one per keyword.  If there are multi-
                 ple 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 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.

     sseeaarrcchh      Search list for host-name lookup.  The search list is normal-
                 ly determined from the local domain name; by default, it be-
                 gins with the local domain name, then successive parent do-
                 mains that have at least two components in their names.  This
                 may be changed by listing the desired domain search path fol-
                 lowing the sseeaarrcchh 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 avail-
                 able for one of the domains.

                 The search list is currently limited to six domains with a
                 total of 256 characters.

     The ddoommaaiinn and sseeaarrcchh 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, separat-
     ed by white space.

FFIILLEESS

     /etc/resolv.conf  The file rreessoollvv..ccoonnff resides in _/_e_t_c.

SSEEEE AALLSSOO
     gethostbyname(3),  resolver(3),  hostname(7),  named(8)

     _N_a_m_e _S_e_r_v_e_r _O_p_e_r_a_t_i_o_n_s _G_u_i_d_e _f_o_r _B_I_N_D.

HHIISSTTOORRYY
     The rreessoollvv..ccoonnff file format appeared in 4.3BSD.

4th Berkeley Distribution        June 5, 1993                                2