Look up a SOA record
Check what DNS returns right now:
Format and example
example.com. 3600 IN SOA ns1.example.net. hostmaster.example.com. 2026110801 7200 3600 1209600 3600- Primary server: The nameserver where the zone is edited (
ns1.example.net.). - Contact: The zone administrator's email, written with a dot instead of @ (
hostmaster.example.com.means hostmaster@example.com). - Serial: A version number. A secondary server copies the zone only when this number goes up. A date plus a counter (
2026110801) is a common scheme. - Refresh, retry, expire: How often a secondary checks for changes (7200 s), how long it waits before retrying a failed check (3600 s), and when it stops answering for a zone it cannot refresh (1209600 s, 14 days).
- Minimum: In practice the negative-caching TTL: how long resolvers remember that a name or record does not exist (3600 s).
Common mistakes
- Editing a zone by hand without raising the serial. Secondary servers keep serving the old version.
- Setting the negative-caching value very high. A record you add later stays invisible to resolvers that already learned it was missing.
- Setting expire lower than refresh, so a secondary can give up on the zone between checks.
- Using a contact address that does not exist, so nobody receives problem reports about the zone.
Related record types
NS record, A record. The DNS record types guide compares them all.