SOA Record (Start of Authority) (SOA Record)
Why SOA Record Is Important
The SOA record controls the operational behavior of your DNS zone. The serial number tells secondary nameservers when the zone has been updated - if the serial does not increment when you make changes, secondaries will not pick up the updates. This is a common source of DNS inconsistency where some nameservers return outdated records.
The timing parameters in the SOA record affect how quickly changes propagate and how resilient your DNS is to primary server outages. The refresh interval determines how often secondaries check for updates. The expire time determines how long secondaries continue serving records if they cannot reach the primary. Setting the expire time too low means secondaries stop responding quickly during an outage.
Most managed DNS providers handle SOA configuration automatically, so you rarely need to modify it directly. However, understanding the SOA is important when debugging propagation issues or migrating between DNS providers.
Checking Your Setup
A DNS health checker shows your SOA record and validates its parameters. Check that the serial number increases with each change, the refresh and retry intervals are reasonable (3600 and 900 seconds are common defaults), and the expire time is long enough to survive a primary server outage.