SOA Record Lookup

Check the Start of Authority record — primary nameserver, contact, serial number and zone timers.

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Enter a domain to check its SOA record
Results will show the zone's authority and timer values

Reading an SOA record

Every DNS zone has exactly one SOA record. It defines who is authoritative for the zone and how secondary nameservers should behave. The fields appear in this order:

  • Primary nameserver — the authoritative source for the zone.
  • Responsible party — an email address with the @ written as a dot.
  • Serial — a version number. It must increase whenever the zone changes, or secondaries will not pick up the update.
  • Refresh / Retry / Expire — how often secondaries check for changes, how soon they retry a failure, and when they stop answering entirely.
  • Minimum TTL — now used as the negative caching TTL: how long a “this name does not exist” answer is cached.

Why the SOA matters when things break

A stale serial is the classic cause of “I changed the record and one nameserver still returns the old value.” If the serial did not increase, secondaries have no reason to transfer the new zone.

A high minimum TTL makes NXDOMAIN answers sticky. If you add a subdomain that was previously missing, resolvers may keep returning “does not exist” for the full negative caching period.

The responsible-party address is worth checking on domains you inherit — it often points at a mailbox nobody reads, which is where CAs and abuse reports go.