SOA Record Lookup
Read a zone’s Start of Authority record — its primary server, serial number and timers.
Your input is used for this one lookup only. It is not logged or stored.
What is an SOA record?
Every DNS zone has exactly one SOA record. It names the primary server and the administrative contact, and carries the serial number and timers that secondary servers use to keep their copies of the zone in sync. It is also where the negative-caching TTL comes from — the one that decides how long a "this name does not exist" answer sticks.
Fields in an SOA record
| Field | Meaning |
|---|---|
| MNAME | The primary (master) name server for the zone. |
| RNAME | The administrator’s email address, written as a domain name — the first dot stands in for the @. |
| Serial | Version number of the zone. It must increase on every change or secondaries will not update. |
| Refresh | How often (seconds) a secondary checks the primary for a new serial. |
| Retry | How long a secondary waits before retrying after a failed refresh. |
| Expire | How long a secondary keeps serving the zone when it cannot reach the primary at all. |
| Minimum | The negative-caching TTL — how long resolvers cache an NXDOMAIN answer for this zone (RFC 2308). |
How to read the results
The SOA is returned as a single row containing all seven fields in the order above. The serial is the field to watch during a change: if you have edited the zone and the serial has not moved, secondaries are still serving the old data. Many providers format the serial as YYYYMMDDnn, but any increasing number is valid.
Rules worth knowing
- A zone has exactly one SOA record, always at the apex.
- The serial must increase on every change. Secondaries compare serials and ignore a zone whose number went backwards.
- RNAME encodes an email address:
hostmaster.example.commeans[email protected]. - The minimum field is not a default TTL — since RFC 2308 it controls negative caching only.
- Querying a subdomain returns the SOA of the enclosing zone, since the subdomain is usually not a zone of its own.
Common problems
| What you see | Usual cause |
|---|---|
| Changes are not reaching secondaries | The serial did not increase. Bump it and the transfer will follow. |
| A deleted name still returns NXDOMAIN after you re-created it | Negative answers are cached for the SOA minimum. Until it expires, resolvers keep saying the name does not exist. |
| You get an SOA for a different name than you asked for | Normal. The answer comes from the closest enclosing zone, so a subdomain query returns the parent zone’s SOA. |
| Very large expire value | Secondaries would serve stale data for a long time during an outage. A week is the common convention. |
Look up another record type
Each record type has its own page with the same explanation of its fields, or use the full DNS Lookup to query every common type at once.
Most often looked up alongside SOA: NS Record Lookup , A Record Lookup , CAA Record Lookup .
Data source: Public DNS-over-HTTPS resolvers. Queries go to the selected public resolver; results reflect that resolver’s cache. Learn about our data sources →
Frequently asked questions
What is an SOA record used for?
What does the serial number mean?
What is the minimum TTL in an SOA record?
Why does the admin email have a dot instead of an @?
hostmaster.example.com means [email protected].