You have an Exchange Server 2013 organization that contains the servers configured as shown in the
following table.

All of the Exchange servers run Windows Server 2012 R2 and are members of a database availability
group (DAG) named DAG1. Each server has a copy of all the mailbox databases.
DAG1 is configured to have a cluster administrative access point. The file share witness is located in
Site A.
You need to identify the maximum number of Mailbox servers that can fail simultaneously without
affecting the mailbox access of the users.
How many servers should you identify?

A.
2

B.
3

C.
4

D.
5

Explanation:
Example: Quorum requires a majority of voters to be able to communicate with each other. Consider
a DAG that has four members. Because this DAG has an even number of members, an external
witness server is used to provide one of the cluster members with a fifth, tie-breaking vote. To
maintain a majority of voters (and therefore quorum), at least three voters must be able to
communicate with each other. At any time, a maximum of two voters can be offline without
disrupting service and data access. If three or more voters are offline, the DAG loses quorum, and
service and data access will be disrupted until you resolve the problem.
Database availability groups
https://technet.microsoft.com/en-us/library/dd979799%28v=exchg.150%29.aspx