What should you add to DNS?

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