Apex domains cannot have CNAME records.
Question and response
Question
dig antic.cm. NS
Answer
antic.cm. 5 NS dns2.antic.cm.
antic.cm. 5 NS dns1.antic.cm.
antic.cm. 5 NS dns3.antic.cm.
Authority
The response has no authority records.
Additional
dns1.antic.cm. 5 A 154.126.129.11
dns2.antic.cm. 5 A 154.126.128.20
dns3.antic.cm. 5 A 41.204.76.227
dns3.antic.cm. 5 A 154.126.128.35
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0