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This feature is designed to increase availability of the DNS service by allowing multiple primaries for a zone. It will not increase overall throughput of DNS update traffic, as ultimately all updates must be replicated to (and processed by) all of the primaries.
When determining which appliances should act as primaries for the zone, consider that an additional SOA record will be required in the database for each primary. This will add to the overall record count for the zone, and each SOA will need to be updated for any change to the zone, which can impact performance.
Enable NTP for all members (at the member level) and ensure that their times are properly synchronized with their local time servers. Ensure that you select the "Exclude the Grid Master as an NTP server" option. The appliance selects the latest zone updates based on the timestamps the updates were made by clients to the primary servers. This is especially important when there are conflicts between two or more zone updates. For information about NTP, see Using NTP for Time Settings /wiki/spaces/nios90draft/pages/319652212.
When specifying the primary server for secondaries, you can choose to have the appliance automatically select it for you based on latency determination or you can manually specify it. When manually selecting a primary for zone updates, consider using one that is close in proximity to the secondary servers, which can result in better service performance. For information about setting preference for the primary server, see Adding Grid Secondaries below.
You can configure a default primary for DDNS updates to a zone with multiple primary servers. To enhance service performance, select a default primary that is close in proximity to the DHCP server that provides DDNS updates. This is especially useful if you have DHCP members that are located in different locations. You can configure a different default primary for each DHCP member based on their locations. For more information, see Defining the Default Primary for DDNS Updates to Zones with Multiple Primaries.
DNSSEC is not supported for zones with multiple primary servers. These zones must be unsigned. For information about DNSSEC, see Configuring DNSSEC.
When determining which appliances should act as primaries for the zone, consider that an additional SOA record will be required in the database for each primary. This will add to the overall record count for the zone, and each SOA will need to be updated for any change to the zone, which can impact performance.
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