DNS SOA Refresh Value

This value configures how often a name server should check it's primary server to see if there has been any updates to the zone which it does by comparing Serial numbers. We issue a warning if it is less than 20 minutes or greater than 12 hours. 

Additional Information

Receiving this warning does not mean that your DNS is failing, but may indicate the set SOA Refresh Value is causing your name servers to not be performing as optimally as recommended. This test will warn you if your name server is checking more or less frequently than recommended, as you may be using a high volume of bandwidth or not checking for updates frequently enough.

RFC 1912:

 Refresh: How often a secondary will poll the primary server to
 see if the serial number for the zone has increased (so it knows
 to request a new copy of the data for the zone).  Set this to
 how long your secondaries can comfortably contain out-of-date
 data.  You can keep it short (20 mins to 2 hours) if you
 aren't worried about a small increase in bandwidth used, or
 longer (2-12 hours) if your Internet connection is slow or is
 started on demand.  Recent BIND versions (4.9.3) have optional
 code to automatically notify secondaries that data has
 changed, allowing you to set this TTL to a long value (one
 day, or more). [RFC 1912]