Check the notifying master before transferring a zone
03A notification prompts a normal SOA query. The secondary compares that answer’s zone serial number with its local copy before deciding whether it needs a transfer.
After a successful transfer, the secondary installs serial 11. Failed transfers do not establish that state. If the checked serial were unchanged, this branch would end without a transfer. The diagram does not implement AXFR/IXFR framing.
Source for this drawing: RFC 1996 · Read RFC source: § 3.11 and related clauses ↗
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For this event, query the known master that sent NOTIFY. Other known masters may still hold old data. RFC1996 §3.11 explicitly distinguishes this from the ordinary refresh sequence.
Read the updated RFC section ↗For a valid SOA NOTIFY, the secondary should act as though the zone reached its refresh interval. Query the known master that sent the event; a different configured master may still hold old data.
- For a valid SOA NOTIFY, the secondary should act as though the zone reached its refresh interval. Query the known master that sent the event; a different configured master may still hold old data.
- If the SOA serial has advanced, a zone transfer, AXFR (full) or IXFR (incremental), should be initiated. RFC1982 supplies wrap-aware serial comparison; ordinary integer ordering is not sufficient.
- Only successful transfer/update work changes the local zone copy. A NOTIFY acknowledgement or its optional Answer cannot do that. Equal serials do not require a new transfer; half-range serial ordering is undefined under RFC1982.
Fictional picnic.example zone and documentation-only addresses. Drawings are schematic; no DNS traffic, server configuration or zone transfer is performed.
Read the RFC section ↗