You have an Exchange Server 2010 organization. You need to recommend a client access solution
that meets the following requirements:
• Reduces the time required for users to reconnect to user mailboxes if a single Client Access server
fails
• Prevents users from being prompted for authentication if a single Client Access server fails
What should you recommend?
A.
Client Access server array and hardware load balancer
B.
database availability group (DAG) and hardware load-balancer
C.
failover clustering and database availability group (DAG)
D.
Windows Network Load Balancing and failover clustering
Explanation:
Understanding Load Balancing in Exchange 2010
Load balancing is a way to manage which of your servers receive traffic. Load balancing provides
failover redundancy to ensure your users continue to receive Exchange service in case of computer
failure. It also enables your deployment to handle more traffic than one server can process while
offering a single host name for your clients.In addition to load balancing, Microsoft Exchange Server 2010 provides several solutions for
switchover and failover redundancy. These solutions include the following:
High availability and site resilience
You can deploy two Active Directory sites in separate geographic locations, keep the mailbox data
synchronized between the two, and have one of the sites take on the entire load if the other fails.
Exchange 2010 uses database availability groups (DAGs) to keep multiple copies of your mailboxes
on different servers synchronized.
Online mailbox moves
In an online mailbox move, end users can access their e-mail accounts during the move. Users are
only locked out of their accounts for a brief time at the end of the process, when the final
synchronization occurs. Online mailbox moves are supported between Exchange 2010 databases and
between Exchange Server 2007 Service Pack 3 (SP3) or a later version of Exchange 2007 and
Exchange 2010 databases. You can perform online mailbox moves across forests or in the same
forest.
Shadow redundancy Shadow redundancy protects the availability and recoverability of messages
while they’re in transit. With shadow redundancy, the deletion of a message from the transport
databases is delayed until the transport server verifies that all the next hops for that message have
completed. If any of the next hops fail before reporting successful delivery, the message is
resubmitted for delivery to the hop that didn’t complete. Load balancing serves two primary
purposes. It reduces the impact of a single Client Access server failure within one of your Active
Directory sites. In addition, load balancing ensures that the load on your Client Access server and
Hub Transport computers is evenly distributed. Architectural Changes in Exchange 2010
Load Balancing Several changes in Exchange 2010 make load balancing important for your
organization. The Exchange RPC Client Access service and the Exchange Address Book service on the
Client Access server role improve the user’s experience during Mailbox failovers by moving the
connection endpoints for mailbox access from Outlook and other MAPI clients to the Client Access
server role instead of to the Mailbox server role. In earlier versions of Exchange, Outlook connected
directly to the Mailbox server hosting the user’s mailbox, and directory connections were either
proxied through the Mailbox server role or referred directly to a particular Active Directory global
catalog server. Now that these connections are handled by the Client Access server role, both
external and internal Outlook connections must be load balanced across the array of Client Access
servers in a deployment to achieve fault tolerance.
A load-balanced array of Client Access servers is recommended for each Active Directory site and for
each version of Exchange. It isn’t possible to share one load-balanced array of Client Access servers
for multiple Active Directory sites or to mix different versions of Exchange or service pack versions of
Exchange within the same array. When you install Exchange 2010 within your existing organization
and configure a legacy namespace for coexistence with previous versions of Exchange, your clients
will automatically connect to the Exchange 2010 Client Access server or server array. The Exchange
2010 Client Access server or Client
Access server array will then proxy or redirect client requests for mailboxes on older Exchange
versions to either Exchange 2003 front-end servers or Exchange 2007 Client Access servers that
match the mailbox version