Apex domains cannot have CNAME records.
Question and response
Question
dig dopplermta1.com. NS
Answer
dopplermta1.com. 5 NS pdns13.domaincontrol.com.
dopplermta1.com. 5 NS pdns14.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0