Your network contains two Exchange Server 2010 Mailbox servers.You create a database availability group （DAG）.You need to ensure that the Exchange servers can replicate mailbox databases.What should you do？（）

• A、Modify the membership list of the DAG
• B、Add the Network Load Balancing feature on both servers
• C、Add Active Directory Federation Services （AD FS） on both servers
• D、Enable Datacenter Activation Coordination （DAC） mode for the DAG