Use the Server app to add a secondary zone to your DNS server.
Make sure the primary server is correctly configured and that zone transfers are enabled on the primary server.
On the secondary server, select DNS in the Server app sidebar.
You can connect to another server by clicking Manage > Connect to Server.
Click Add , then choose Add Secondary Zone from the pop-up menu.
In the Name field, enter the zone name.
The zone name is the same as the primary zone defined on the primary name server.
Below the Primary Servers list, click Add .
Enter the IP addresses for each primary server in the secondary zone.
Click Create.