Apex domains cannot have CNAME records.
Question and response
Question
dig mailsecurity.fr. NS
Answer
mailsecurity.fr. 1 NS ns1.webaxys.net.
mailsecurity.fr. 1 NS ns2.webaxys.net.
Authority
The response has no authority records.
Additional
ns1.webaxys.net. 1 A 217.71.121.155
ns2.webaxys.net. 1 A 91.198.199.3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0