Issue with Outlook Autodiscover CNAME Record

My client wants to setup their email for Outlook and I have added all the DNS records for their website. Their IT person is handling the setup and sent me the DNS zone records for Outlook.

Their IT person says they can see all of the records except the CNAME records. I've tested several of my sites on mxtoolbox.com and cannot get CNAME records to show up.

Any reason why the CNAME records would not be visible or accessible?

Hello,

Probably the zone was not loaded due to errors, I see the zone has serial 2016051104. Does it match the one from db file?
What you see if you restart named/bind from console?

A good tool to test autodiscover http://testconnectivity.microsoft.com/