The Refresh Interval (REFRESH) is a field found in the Start of Authority (SOA) record of a DNS (Domain Name System) zone. It specifies the amount of time (in seconds) that secondary DNS servers should wait before attempting to refresh their copy of the zone data from the primary DNS server.
Here’s what the REFRESH field in the SOA record signifies:
- Zone Data Update: The REFRESH value defines how often secondary DNS servers should contact the primary DNS server to check if there have been any updates or changes to the zone data.
- Zone Synchronization: It ensures that secondary servers regularly synchronize their zone data with the primary server to ensure they have the most up-to-date information. If changes occur within the zone, the secondary servers will know to retrieve the latest data during the refresh.
- Zone Consistency: By specifying a reasonable REFRESH interval, administrators can ensure that secondary servers maintain accurate and consistent zone data. This is crucial for the proper functioning of DNS and to prevent discrepancies or outdated information.
In summary, the REFRESH interval in the SOA record determines how often secondary DNS servers should request an update of the zone data from the primary server. This periodic synchronization helps maintain data consistency and ensures that secondary servers have access to the most current DNS information.