You are a messaging professional for Contoso, Ltd.

Your company has a Microsoft Exchange Server 2007 computer named Server1 with the Client Access Server role. You have a second Exchange Server 2007 computer named Server2 with the Mailbox server role. You also have a single Exchange Server 2003 computer named Server3. Some mailboxes are on Server2 and some are on Server3. All users have been instructed to access Microsoft Outlook Web Access (OWA) by using https://owa.contoso.com/exchange, which is a DNS alias pointing to Server1.

You are creating a plan to provide OWA fault tolerance for all users who are using the fewest number of servers.

You need to make the OWA logon experience transparent for users on both the Exchange Server 2003 computer and the Exchange Server 2007 computer without any disruption or reconfiguration for end users.

What should you do to make the OWA logon experience transparent for users on both the Exchange Server 2003?

A.
Create a Network Load Balancing (NLB) cluster by using Server2 and Server3. Modify the DNS alias
owa.contoso.com to point to the NLB cluster.

B.
Instruct the users of the Exchange Server 2003 computer to use the URL https:  //server3.contoso.com/exchange. Instruct users of the Exchange Server 2007 computer to use the URL https://server1.contoso.com/owa.

C.
Install the Client Access Server role on Server2. Create a Network Load Balancing (NLB) cluster by using Server1 and Server2. Modify the DNS alias owa.contoso.com to point to the NLB cluster.

D.
Install a new Exchange Server 2007 computer named Server 4 with the Client Access Server role.
Implement Network Load Balancing (NLB) between Server1 and Server4. Modify the DNS alias
owa.contoso.com to point to the NLB cluster.