PUBLIC DNS
Look up the SOA record.
Read the start-of-authority record for serial, refresh, retry, expire, and minimum TTL.
SOA describes the authoritative zone. Serial changes after edits; minimum TTL influences negative caching.
SOA is not an MX or authentication check. It does not tell you where mail is delivered. For a scored MailerZ readiness scan across MX, leftover routes, SPF, DKIM, and DMARC, use Troubleshooting.
Open the full DNS diagnostic · Simulate a route in the Email Routing Lab
Cited standard: RFC 1035
SOA describes the authoritative zone. Serial changes after edits; minimum TTL influences negative caching.