RFC 2136 (rfc2136) - Page 3 of 26

Dynamic Updates in the Domain Name System (DNS UPDATE)

RFC 2136                       DNS Update                     April 1997


      CNAME  compare only NAME, CLASS, and TYPE -- it is not possible
             to have more than one CNAME RR, even if their data fields
             differ.

   1.2 - Glue RRs

   For the purpose of determining whether a domain name used in the
   UPDATE protocol is contained within a specified zone, a domain name
   is "in" a zone if it is owned by that zone's domain name.  See
   section 7.18 for details.

   1.3 - New Assigned Numbers

      CLASS = NONE (254)
      RCODE = YXDOMAIN (6)
      RCODE = YXRRSET (7)
      RCODE = NXRRSET (8)
      RCODE = NOTAUTH (9)
      RCODE = NOTZONE (10)
      Opcode = UPDATE (5)

2 - Update Message Format

   The DNS Message Format is defined by [RFC 1035 4.1].  Some extensions
   are necessary (for example, more error codes are possible under
   UPDATE than under QUERY) and some fields must be overloaded (see
   description of CLASS fields below).

   The overall format of an UPDATE message is, following [ibid]:

      +---------------------+
      |        Header       |
      +---------------------+
      |         Zone        | specifies the zone to be updated
      +---------------------+
      |     Prerequisite    | RRs or RRsets which must (not) preexist
      +---------------------+
      |        Update       | RRs or RRsets to be added or deleted
      +---------------------+
      |   Additional Data   | additional data
      +---------------------+










Vixie, et. al.              Standards Track