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.
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.
Related DNS tools
Check DNS records worldwide across independent public resolvers for A, AAAA, CNAME, MX, TXT, NS, SOA, PTR, SRV and CAA answers.
Check DNS propagation worldwide and compare record values, status and latency across independent global DNS resolvers.
Run a global A record lookup to check IPv4 addresses, TTL values and propagation across independent DNS resolvers.
Check AAAA records worldwide to verify IPv6 addresses, propagation, TTL behavior and resolver differences before or after a dual-stack change.
Check CNAME records worldwide, compare canonical targets across public DNS resolvers and detect stale aliases after CDN, SaaS or hosting changes.
Check MX records worldwide, compare mail server hostnames and priorities, and diagnose email delivery or migration issues across global DNS resolvers.