SOA Refresh Value
Tests that the Start of Authority (SOA) refresh value is in the recommended range.
The Start of Authority (SOA) record is a special DNS record that lists certain administrative information about the domain name and helps with coordinating zone transfers. Zone transfers are how a cluster of servers can coordinate on updating information.
The Refresh value is the number of seconds that a secondary server should wait before asking the primary server if there has been an update. The recommended values differ depending who you ask, but are somewhere between 1 hour (3600s) and 1 day (86400s). This test will only be marked as a failure if the refresh value is shorter than 15 minutes (900s) or longer than 2 days (172800s).
The primary server should have the capability of notifying the secondary servers whenever there is a change, making this refresh process unnecessary. Depending on your DNS provider, is likely that you do not have control over setting the values of the SOA record.