Apex domains cannot have CNAME records.
Question and response
Question
dig wanadoo.fr. NS
Answer
wanadoo.fr. 5 NS ns2.orange.fr.
wanadoo.fr. 5 NS ns4.orange.fr.
wanadoo.fr. 5 NS ns3.orange.fr.
Authority
The response has no authority records.
Additional
ns2.orange.fr. 5 A 80.10.202.224
ns2.orange.fr. 5 AAAA 2a01:cb09:2040:6:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0