Apex domains cannot have CNAME records.
Question and response
Question
dig easynet.fr. NS
Answer
easynet.fr. 5 NS ns0.easynet.co.uk.
easynet.fr. 5 NS ns.easynet.fr.
easynet.fr. 5 NS ns1.easynet.co.uk.
Authority
The response has no authority records.
Additional
ns.easynet.fr. 5 A 199.116.149.29
ns0.easynet.co.uk. 5 A 195.40.1.250
ns1.easynet.co.uk. 5 A 195.40.0.250
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0