The authoritative source for the zone — the server other authoritative nameservers replicate from. Not necessarily the same as what clients query.
SOA Record Lookup — the master record for any DNS zone.
Query the SOA (Start of Authority) record for a domain in real time. Returns the primary nameserver, the administrator email (converted from dot-format to @), the serial number tracking zone version, and the four timing fields (refresh, retry, expire, minimum) that control how secondary nameservers replicate the zone. Every zone must have exactly one SOA at its apex.
Look up an SOA record
Authoritative query. Every field decoded — no BIND-format cryptic dumps.
What the SOA lookup shows
Contact for zone-management issues. The raw SOA format uses `.` instead of `@` because `@` has special meaning in BIND zone files. This tool converts it back for display.
Incremented on every edit. Modern convention: YYYYMMDDNN. Every edit bumps the counter; secondaries poll and pull fresh when they see a higher number.
How often secondaries poll the primary (refresh), the wait time after a failed poll (retry), and how long a secondary keeps serving the zone if it can't reach the primary at all (expire).
Historically the default TTL for the zone; now specifically the negative-cache TTL — how long resolvers remember 'this name does not exist' answers.
Flags whether the serial follows the YYYYMMDDNN convention or uses an opaque incrementing counter. Both work — YYYYMMDDNN is more auditable.
When to look up SOA
- Zone-transfer diagnostics If secondaries aren't updating, compare serial numbers between primary and secondary. If they match, replication is working; if primary is higher, the secondary can't reach the primary.
- Zone-edit forensics The serial number in YYYYMMDDNN format tells you exactly when the zone was last edited. Useful for correlating with incident timelines.
- Nameserver-migration verification After migrating DNS to a new host, confirm the SOA reflects the new provider (primary NS + admin email should update).
- TTL-planning reference The minimum TTL field is the negative-cache TTL — critical when you're planning to delete a record and want to know how long resolvers will remember it's gone.
- Registrar-level troubleshooting When something's broken at the registry level, the SOA is the first record to check — an incorrect MNAME can cause propagation issues across the zone.
Common questions
- What is an SOA record? The master record for a DNS zone. Names the primary authoritative server, the zone administrator's email, a serial number tracking zone-file version, and four timing fields for zone replication. Every zone must have exactly one SOA at the apex.
- What does the serial number do? Secondaries poll the primary and compare serial numbers. If the primary's serial is higher, secondaries pull a fresh copy of the zone. Every edit must bump the serial monotonically or replication won't trigger.
- Why is the admin email in dot format? The DNS SOA format uses `.` as the local-part separator instead of `@` — a hangover from BIND zone-file syntax where `@` means 'current origin'. Tools should convert on display.
- What's the difference between refresh and retry? `refresh` = normal poll interval (seconds). `retry` = the wait after a failed poll before retrying — typically shorter than refresh so you catch primaries recovering quickly.
- Is SOA the same as NS? No. SOA names the primary and defines zone timing. NS lists every authoritative server (primary + all secondaries). Both are mandatory at the zone apex.
Related DNS tools
See every authoritative nameserver for the zone, alongside SOA.
Verify whether the zone is DNSSEC-signed.
See who owns the zone at the registrar level.
Full DNS dump — every record type at once.