You have an Exchange Server 2013 organization that contains three Client Access servers named EX1, EX2,
and EX3. The organization also contains eight Mailbox servers.
All users have client computers that have Microsoft Outlook 2013 installed.
You create a Network Load Balancing (NLB) cluster and add all of the Client Access servers as hosts in the
cluster. The cluster has the following configurations:
The default host is set to EX1.
A port rule is configured for HTTPS traffic.
The port rule has the affinity parameter set to Single.
The port rule has the filtering mode set to Single host.
The port rule has the Handling priority set to the default option.
You discover that Outlook always connects to EX1.
You need to ensure that client connection are handled by all three Client Access servers.
What should you modify?

A.
the affinity parameter of the port rule.

B.
the filtering mode of the port rule.

C.
the default host of the cluster.

D.
the handling priority of the port rule.

Explanation:
https://technet.microsoft.com/en-us/library/cc778263(v=ws.10).aspx