DNS dynamic update defines a new DNS opcode, new DNS request and response structure if that opcode is used, and new error codes. An update can specify complex combinations of deletion and insertion (with or without pre-existence testing) of resource records (RRs) with one or more owner names; however, all testing and changes for any particular DNS update request are restricted to a single zone. Updates occur at the primary server for a zone.
The primary server for a secure dynamic zone must increment the zone SOA serial number when an update occurs or the next time the SOA is retrieved if one or more updates have occurred since the previous SOA retrieval and the updates themselves did not update the SOA.