A.Install the antivirus software on each mailbox storage server
B.Install the antivirus software on each Outlook Web Access server
C.Install the antivirus software on one Outlook Web Access server at each office
D.Install the antivirus software on a back-end server that contains no mailboxes

A.Configure the front-end servers in each branch office to be members of a new Active Directory site
B.Configure the back-end servers to have server encryption certificates issued by a commercial certification authority （CA）
C.Configure two back-end servers to be members of a Network Load Balancing cluster. Configure Network Load Balancing for inbound RPC connections
D.Configure multiple front-end servers in each branch office to be members of a Network Load Balancing cluster. Configure Network Load Balancing for inbound HTTPS connections