Your company has a data center. The data center contains a server that has Exchange Server
2016 and the Mailbox server role installed. Outlook anywhere clients connect to the Mailbox server
by using the name outlook.contoso.com. The company plans to open a second data center and to
provision a database availability group (DAG) that spans both data centers. You need to ensure
that Outlook Anywhere clients can connect if one of the data centers becomes unavailable. What
should you add to DNS?

A.
one A record

B.
two TXT records

C.
two SRV records

D.
one MX record

Explanation:
https://technet.microsoft.com/en-gb/library/dd638104(v=exchg.150).aspx?f=255&MSPPError=-
2147217396