You are a messaging professional for A. Datum Corporation. Your company uses a Microsoft Exchange Server 2007 messaging system.

Your company has a main office and four branch offices. Each office has a connection to the Internet.

Exchange Server 2007 computers are deployed in each office. One Client Access Server is deployed in each office. Only the Client Access Server at the main office is accessible from the Internet. All the users access the Client Access Server by using the Fully Qualified Domain Name (FQDN) mail.adatum.com.

Your company has 1,500 users. The users access their Exchange mailboxes by using Microsoft Outlook Web Access and Microsoft Office Outlook Anywhere from the Internet. The user mailboxes are located on the Exchange Server 2007 computers in all the five offices.

The company policy requires that the impact of any single Client Access Server failure must be restricted to the minimum possible number of users.

You need to meet the outlined requirement. You want to achieve this goal without changing the message client configuration.

What should you do to require that the impact of any single Client Access Server failure must be restricted to the minimum possible number of users.?

A.
Modify the network configuration so that the Client Access Servers in each office are accessible from
the Internet. Configure unique host records for all the Client Access Servers on the Internet Domain Name System (DNS) server.

B.
Modify the network configuration so that the Client Access Servers in each office are available from the Internet. Configure alias records for mail.adatum.com for the Client Access Server in each office on the (DNS) server.

C.
Deploy an additional Client Access Server at each branch office, and configure these Client Access servers in Network Load Balancing (NLB) clusters.

D.
Deploy an additional Client Access Server at the main office. Configure both the Client Access Servers
located in the main office in a Network Load Balancing (NLB) cluster.