Apex domains cannot have CNAME records.
Question and response
Question
dig FR. NS
Answer
FR. 5 NS g.ext.nic.fr.
FR. 5 NS d.nic.fr.
FR. 5 NS f.ext.nic.fr.
Authority
The response has no authority records.
Additional
d.nic.fr. 172353 A 194.0.9.1
f.ext.nic.fr. 105231 A 194.146.106.46
g.ext.nic.fr. 50028 A 194.0.36.1
d.nic.fr. 172353 AAAA 2001:678:c:0:0:0:0:1
f.ext.nic.fr. 105231 AAAA 2001:67c:1010:11:0:0:0:53
g.ext.nic.fr. 50028 AAAA 2001:678:4c:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0