Apex domains cannot have CNAME records.
Question and response
Question
dig mon-salaire-en-net.fr. NS
Answer
mon-salaire-en-net.fr. 5 NS ruth.ns.cloudflare.com.
mon-salaire-en-net.fr. 5 NS chris.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0