Apex domains cannot have CNAME records.
Question and response
Question
dig cloudcone.email. NS
Answer
cloudcone.email. 3 NS ac2.cloudcone.net.
cloudcone.email. 3 NS ac1.cloudcone.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0