Apex domains cannot have CNAME records.
Question and response
Question
dig netanswer.fr. NS
Answer
netanswer.fr. 5 NS ns1.cusae.com.
netanswer.fr. 5 NS ns0.cusae.com.
Authority
The response has no authority records.
Additional
ns0.cusae.com. 3 A 91.109.120.131
ns1.cusae.com. 3 A 91.109.120.132
ns0.cusae.com. 3 AAAA 2a01:66c0:1:0:0:0:53:1
ns1.cusae.com. 3 AAAA 2a01:66c0:1:0:0:0:53:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0