SOA Record Lookup

Check SOA (start of authority) records for any DNS zone across 12 global resolvers. Free real-time DNS checker.

What is an SOA record?

An SOA record ("start of authority") sits at the apex of every DNS zone and carries metadata about the zone: the primary nameserver, the responsible-party email, and a set of timing parameters (serial, refresh, retry, expire, minimum TTL). Every DNS zone has exactly one SOA.

When to check the SOA

• Diagnosing whether a zone change has actually been published (the SOA serial typically increments on each change)
• Confirming which nameserver is currently the primary
• Auditing zone-wide TTL and refresh settings

Reading the results

An SOA record value packs seven fields into one string: mname rname serial refresh retry expire minimum. mname is the primary nameserver, rname is the responsible-party email (with . instead of @), and the rest are timing parameters in seconds.

Common errors and pitfalls

• Serial doesn't increment after a change: most modern providers handle this automatically, but on legacy bind setups you have to bump it manually. If the serial doesn't change, secondary nameservers won't pull the new zone data.
• Different SOAs across resolvers: usually one resolver has a slightly stale cache. Wait one minimum-TTL window and re-check.
• rname has a literal @: that's a common typo. The "@" must be encoded as a dot in the SOA, so admin@example.com becomes admin.example.com..
• Negative cache TTL too high: the "minimum" field controls how long resolvers cache NXDOMAIN answers. Set it to 300–3600 seconds for fast iteration during DNS work.

FAQ

What does the SOA serial number mean?

It's a version counter for the zone. By convention it's a date-style integer (YYYYMMDDNN), incremented every time the zone changes. Secondary nameservers compare serials to decide whether to pull a fresh zone copy from the primary.

Why does the SOA serial differ across resolvers?

The newest serial is what the primary nameserver actually has. Resolvers may serve a slightly older serial until their cache (governed by the SOA's minimum-TTL field) refreshes.

What does each timing field mean?

refresh: how often secondaries check the primary for changes. retry: how often to retry if refresh fails. expire: how long secondaries serve stale data when the primary is unreachable. minimum: TTL for negative responses (NXDOMAIN/NODATA).

Can a zone have multiple SOA records?

No. Exactly one SOA per zone, at the apex.

Background reading

See DNS zones for theory and the DNS Records Explained guide for context.