You are the messaging engineer for your company. Your company has a Microsoft Exchange Server 2003 messaging system.
Your company has two Exchange Server 2003 front-end servers deployed in a Network Load Balancing cluster, as shown in the following diagram:
You plan to install Exchange Server 2007 Client Access servers on your network. Exchange Server 2007 Mailbox and Hub Transport servers will be installed simultaneously.
You need to plan for the deployment of the Client Access servers.
What should you do?
A.
Install one Client Access server. Join the server to the Network Load Balancing cluster.
B.
Replace the Exchange Server 2003 front-end servers with two Client Access servers. Create a new Network Load Balancing cluster that includes the two Client Access servers.
C.
Remove one Exchange Server 2003 front-end server. Install a new Client Access server with the same name and IP address as the server that was removed.
D.
Install two Client Access servers. Create a new Network Load Balancing cluster that includes the two Client Access servers and the two Exchange Server 2003 front-end servers.
Explanation:
The CAS role provides functionality similar to that of a 2003 FE server. You must deploy this role if you have clients that access mail by OWA, IMAP4, POP3, or mobile devices. This role can coexist with Exchange 2000 and 2003 servers.You must have at least one CAS in each AD site hosting a Mailbox Server. The role can be configured for internal access or be Internet-facing, named "First CAS". A CAS can act as a proxy for other CASs in the organization and perform redirection for OWA URLs. This is useful when multiple such servers exist in different AD sites and only one is exposed to the Internet.
Whether a user sees the 2003 or 2007 OWA client depends on where his mailbox is stored. For example, if the mailbox is hosted on a 2003 BE server, he sees the 2003 version of OWA.
The correct URL to reach OWA also depends on what server hosts the mailbox. For a 2003 BE server, use: http://<servername>/Exchange. For a 2007 Mailbox server, use either: http://<servername>/owa or http://<servername>/Exchange.
The version of ActiveSync a client employs also depends on the Mailbox server version. For Direct Push to be enabled, the mailbox must be located on a server running 2003 SP2 or 2007.
Before decommissioning your 2003 FE servers, decide if you want to preserve any OWA custom settings. Since the 2007 CAS requires installation on fresh hardware, no 2003 configuration is retained.
Typically, you transition all the servers in a single routing group or AD site at the same time, then configure coexistence with other sites. First, replace all Exchange 2003 FE servers with Exchange 2007 CASs. FE servers communicate with the BE servers over HTTP. CASs communicate with mailbox servers over RPC. So, using 2003 FE servers together with 2007 Mailbox servers isnt supported.
After establishing the CASs, deploy the Hub servers, configure whatever Send and Receive and Routing Group connectors are required. Then, transfer mailboxes to 2007 Mailbox servers.
http://www.msexchange.org/articles_tutorials/exchange-server-2007/high-availability-recovery/load-balancing-exchange-2007-client-access-servers-windows-network-technology-part1.html
http://technet.microsoft.com/en-us/library/aa998186.aspx
http://technet.microsoft.com/en-us/library/bb124350.aspx
http://msexchangeteam.com/archive/2007/09/04/446918.aspx