SOA Record

The SOA (Start of Authority) record is a mandatory DNS record at the top of every DNS zone. It contains administrative information including the primary nameserver, the email address of the zone administrator, a serial number that increments with each change, and timing values that control how often secondary nameservers check for updates. While you rarely need to edit SOA records directly, the serial number is important: secondary nameservers use it to know when zone data has changed.