Apex domains cannot have CNAME records.
Question and response
Question
dig monoperateurlocal.fr. NS
Answer
monoperateurlocal.fr. 5 NS ns1.ornethd.net.
Authority
The response has no authority records.
Additional
ns1.ornethd.net. 5 A 213.226.72.249
ns1.ornethd.net. 5 AAAA 2a0a:7980:a:0:0:0:0:249
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0