SOA Lookup

The SOA Lookup tool returns the Start of Authority record for any DNS zone. The SOA is the single most important record in a zone — it identifies the primary nameserver, the zone administrator's contact address, the current serial number, and the timers that control zone replication and negative caching. Every authoritative DNS server for a zone must publish a matching SOA, and every recursive resolver uses the SOA to decide how long to cache a 'no such record' answer.

We parse the seven fields defined in RFC 1035: primary NS, admin email (rendered from the DNS-encoded form back to a normal address), serial number, refresh, retry, expire, and minimum TTL. Where the serial follows the YYYYMMDDNN convention we also decode it into a human date, so you can spot stale zones at a glance. All timers are shown in both raw seconds and a friendly h/m/d rendering.

Use SOA Lookup when you migrate DNS providers (the primary NS should match your new provider), when diagnosing slow updates (the minimum TTL controls negative caching), when investigating replication lag between primary and secondary nameservers, or when auditing whether a zone is actually managed where you think it is. Pair with NS Lookup for the delegation chain and with the DNS Propagation Checker to confirm resolvers around the world see the new SOA serial.