When you import an AD-integrated zone into Address Manager, the server from which you are importing is assigned the AD-Integrated Master deployment role for the zone.
Any additional Name Server records present in the zone are imported as Slave 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 slave 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 Master zone and server2 is assigned the Slave 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 Slave deployment role changes to AD-Integrated Master. After you import from server1 and server2, both deployment roles are set to AD-Integrated Master.