RFC 2136 (rfc2136) - Page 3 of 26
Dynamic Updates in the Domain Name System (DNS UPDATE)
Alternative Format: Original Text Document
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
