These messages are part of the authoritative section of the response to a DIG query that requested authority records. The following list defines each of the values:

• Serial is the serial number of the zone database.
• Refresh is the refresh interval, or the length of time, in seconds, you must allow between the refreshing of a database from a remote name server.
• Retry is the retry interval that indicates the length of time, in seconds, you must allow before trying a failed refresh again.
• Expire is the expiration time-to-live that indicates the maximum time for records to be valid in the zone database.
• Minim is the minimum time-to-live that indicates the minimum time for records to be valid in the zone database.