After the secondary DNS has been enabled, if the configuration changes on your primary DNS, you need to go to the Basic DNS page in the Alibaba Cloud DNS console and find the specified domain. You can then click Modify Parameters to update the configuration of the secondary DNS. For more information, see step 8 of steps in Enable Secondary DNS.
After the configuration changes are completed, the secondary DNS will send connection requests to obtain the latest resource records from the primary DNS.
If Primary and Secondary DNS Connection is Disconnected, you need to check if the parameter settings of the secondary DNS are correct, or the primary DNS is running and accessible from the external network. After you have fixed the issue, you can click Connect to Primary DNS to establish the connection to the primary DNS.
If the connection is successfully established, the system synchronizes the latest resource records on the primary DNS to the secondary DNS, and updates the connection status between these two DNS servers.