SOA record
The "start of authority" for a zone: primary nameserver, administrative contact, serial number and the timers that govern secondary servers.
What one looks like
example.com. 3600 IN SOA ns1.provider.com. hostmaster.example.com. 2026082601 7200 3600 1209600 3600
Things worth knowing
- The serial number should increase with every zone edit; secondaries use it to know they must update.
- The final number is the negative caching TTL — how long a "does not exist" answer is remembered.
- Every zone has exactly one SOA.
Look up a real SOA record
Query any domain live and see every record type with its TTL.