Apex domains cannot have CNAME records.
Question and response
Question
dig ucad.sn. NS
Answer
ucad.sn. 5 NS ns.ucad.sn.
ucad.sn. 5 NS ns-a.unchk.sn.
ucad.sn. 5 NS ns2.ucad.sn.
ucad.sn. 5 NS ns1.ucad.sn.
Authority
The response has no authority records.
Additional
ns.ucad.sn. 95215 A 196.1.95.1
ns1.ucad.sn. 5 A 196.1.92.2
ns2.ucad.sn. 5 A 154.65.39.6
ns-a.unchk.sn. 5 A 102.36.138.88
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0