Apex domains cannot have CNAME records.
Question and response
Question
dig mta3.net. NS
Answer
mta3.net. 5 NS pdns10.domaincontrol.com.
mta3.net. 5 NS pdns09.domaincontrol.com.
Authority
The response has no authority records.
Additional
pdns09.domaincontrol.com. 2 A 97.74.110.54
pdns10.domaincontrol.com. 2 A 173.201.78.54
pdns09.domaincontrol.com. 2 AAAA 2603:5:21e2:0:0:0:0:36
pdns10.domaincontrol.com. 2 AAAA 2603:5:22e2:0:0:0:0:36
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0