Apex domains cannot have CNAME records.
Question and response
Question
dig nic.fr. NS
Answer
nic.fr. 5 NS ns1.ext.nic.fr.
nic.fr. 5 NS ns6.ext.nic.fr.
nic.fr. 5 NS ns4.nic.fr.
nic.fr. 5 NS ns7.ext.nic.fr.
Authority
The response has no authority records.
Additional
ns1.ext.nic.fr. 5 A 193.51.208.13
ns4.nic.fr. 5 A 192.134.4.19
ns6.ext.nic.fr. 5 A 130.59.31.29
ns7.ext.nic.fr. 5 A 194.0.36.1
ns4.nic.fr. 5 AAAA 2001:67c:2218:2:0:0:4:19
ns6.ext.nic.fr. 5 AAAA 2001:620:0:ff:0:0:0:2f
ns7.ext.nic.fr. 5 AAAA 2001:678:4c:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0