About

The SOA (Start of Authority) record is a required record at the beginning of every DNS zone. It contains important administrative information about the zone, including the primary name server, the email address of the domain administrator, and various timing parameters for zone transfers and caching.

Every DNS zone must have exactly one SOA record. It's automatically created when you set up a new zone and is typically managed by your DNS provider. The SOA record is crucial for DNS zone transfers between primary and secondary name servers.

The serial number in the SOA record is particularly important - it must be incremented every time the zone is updated, so secondary servers know when to request a zone transfer.

Format & Example

Record Format

domain.com. IN SOA ns1.domain.com. admin.domain.com. (serial refresh retry expire minimum)

Example

example.com. IN SOA ns1.example.com. hostmaster.example.com. 2024011501 7200 3600 1209600 86400

Primary NS is ns1.example.com, admin email is [email protected], serial 2024011501, refresh every 2 hours, retry after 1 hour, expire after 2 weeks, minimum TTL of 1 day.

Common Uses

•Required record for every DNS zone
•Zone transfer coordination between name servers
•Defining negative caching behavior
•Administrative contact information

Best Practices & Tips

•Serial number format: YYYYMMDDnn (date + revision number)
•Always increment serial when making zone changes
•The admin email uses a dot instead of @ (admin.example.com = [email protected])
•Usually managed automatically by your DNS provider

Related Record Types

NS A

Related Tools

Propagation

Verify SOA settings

Start of Authority Record