RFC 2182 (rfc2182) - Page 3 of 12

Selection and Operation of Secondary DNS Servers

RFC 2182    Selection and Operation of Secondary DNS Servers   July 1997


   Reverse Zone           A zone containing data used to map addresses
                          to names.

   Server                 An implementation of the DNS protocols able to
                          provide answers to queries.  Answers may be
                          from information known by the server, or
                          information obtained from another server.

   Authoritative Server   A server that knows the content of a DNS zone
                          from local knowledge, and thus can answer
                          queries about that zone without needing to
                          query other servers.

   Listed Server          An Authoritative Server for which there is an
                          "NS" resource record (RR) in the zone.

   Primary Server         An authoritative server for which the zone
                          information is locally configured.  Sometimes
                          known as a Master server.

   Secondary Server       An authoritative server that obtains
                          information about a zone from a Primary Server
                          via a zone transfer mechanism.  Sometimes
                          known as a Slave Server.

   Stealth Server         An authoritative server, usually secondary,
                          which is not a Listed Server.

   Resolver               A client of the DNS which seeks information
                          contained in a zone using the DNS protocols.

3. Secondary Servers

   A major reason for having multiple servers for each zone is to allow
   information from the zone to be available widely and reliably to
   clients throughout the Internet, that is, throughout the world, even
   when one server is unavailable or unreachable.

   Multiple servers also spread the name resolution load, and improve
   the overall efficiency of the system by placing servers nearer to the
   resolvers.  Those purposes are not treated further here.

   With multiple servers, usually one server will be the primary server,
   and others will be secondary servers.  Note that while some unusual
   configurations use multiple primary servers, that can result in data
   inconsistencies, and is not advisable.





Elz, et al.              Best Current Practice