What this check shows
The Start of Authority record contains the primary nameserver, responsible mailbox, serial number and timing values for a DNS zone.
SOA comparisons are particularly useful when checking whether secondary authoritative servers have received the latest zone version.
When to use it
- Checking zone transfer consistency
- Comparing SOA serial numbers
- DNS provider migrations
- Investigating stale authoritative data
How to read the result
- Different serial numbers can indicate that authoritative servers are serving different zone versions.
- Refresh, retry and expire values control secondary server behavior rather than ordinary browser caching.
- A recursive resolver may cache an older SOA response until its TTL expires.
Command examples
Use these dig commands when you need to compare DNSRadar with a terminal check or collect evidence for a DNS provider.
Terminal
dig example.com SOA +short
dig @1.1.1.1 example.com SOA
dig @ns1.example.net example.com SOA +norecurseQuestions
What does the SOA serial mean?
It identifies a version of the zone. Secondary nameservers use it to decide whether a zone transfer is needed.
Must the serial look like a date?
No. Date-based serials are conventional, but any correctly increasing 32-bit serial strategy can be valid.