Apex domains cannot have CNAME records.
Question and response
Question
dig eurafibre.fr. NS
Answer
eurafibre.fr. 5 NS meera.ns.cloudflare.com.
eurafibre.fr. 5 NS jerome.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0