When you import an AD-integrated zone into Address Manager, the server from which you are importing is assigned the AD-Integrated primary deployment role for the zone.
Any additional Name Server records present in the zone are imported as secondary Deployment roles. This is because Address Manager cannot determine whether or not zones on the additional name servers are stored in Active Directory, or are secondary zones.
For example, assume that you have two servers (server1.example.com, and server2.example.com) hosting an AD-integrated zone. If you import from server1 first, the import process assigns the zone two DNS deployment roles: server1 is assigned the AD-integrated primary zone and server2 is assigned the secondary deployment role. This is because the import process uses the Name server records to build the list of roles. After the initial import from Windows 1 the roles appear in the Deployment Roles section of the DNS Zone page.
When you import from server2, the secondary deployment role changes to AD-Integrated primary. After you import from server1 and server2, both deployment roles are set to AD-Integrated primary.