You are the messaging engineer for your company.

You plan to deploy Exchange Server 2007.

You need to recommend the number of Exchange Server 2007 servers required to meet the following requirements:

Support for Exchange ActiveSync.
If a server fails on any Exchange server, continue to provide message delivery and access to mailboxes.
Minimize the number of Exchange Server 2007 servers installed on your network.

How many Exchange Server 2007 servers should you recommend?

A.
Two servers

B.
Three servers

C.
Four servers

D.
Five servers

E.
Six servers

Explanation:
If a role fails on any Exchange server, continue to provide delivery and access to mailboxes. This requires a Mailbox cluster. Support for ActiveSync requires a CAS. Every site must have at least one Hub server. Fault tolerance then calls for a fourth machine to duplicate the Hub and CAS roles.