You are the messaging engineer for your company. Your company has one office that has 1,500 users.

You plan to deploy Exchange Server 2007 on three servers: Server1, Server2, and Server3. Server1 will contain the Mailbox Server role. Server2 will contain the Hub Transport role. Server3 will contain the Client Access Server role. Concurrent connections to Client Access servers do not exceed 1,200 users.

All servers are configured with identical hardware. The hardware for the three servers is configured as described in the following table.
You need to recommend changes to the existing server hardware to decrease the response time for client requests generated from Microsoft Office Outlook 2007 and Outlook Web Access.

What should you recommend?

A.
Increase the number of processors for the Mailbox server role.

B.
Increase the amount of physical memory for the Client Access server role.

C.
Increase the amount of disk storage space for the Client Access server role.

D.
Increase the amount of disk storage space for the Hub Transport server role.

Explanation:
The recommended configuration for the Mailbox role is based on mailbox count and user profile. A 4x processor core server provides a good balance between price and performance, and should be able to host several thousand mailboxes.

http://technet.microsoft.com/en-us/library/aa998874.aspx

In general, memory utilization on CASs has a linear relationship to the number of client connections and the transaction rate. Based on current recommendations for processor and memory configurations (2 GB per core (2 GB minimum)), a CAS will be balanced in terms of memory and processor utilization, and become processor bound at approximately the same time it becomes memory bound.

http://technet.microsoft.com/en-us/library/bb738124.aspx

With only one office, the Hub role isnt critical.