Which type of DNS record for the Autodiscover service is required?

You are an IT assistant for a local real estate company. The company is configuring Microsoft Office 365 for email services. You want to enable other organizations to send email for your organization to Microsoft Exchange Online services.

Which type of DNS record for the Autodiscover service is required?
A . CNAME
B . SRV
C . MX
D . HOST

Answer: A

Explanation:

The CNAME record helps Outlook clients to easily connect to the Exchange Online service by using the Autodiscover service. Autodiscover automatically finds the correct Exchange Server host and configures Outlook for users. Reference: External DNS records required for Exchange Online

http://howtonetworking.com/msapps/office365-11.htm