Apex domains cannot have CNAME records.
Question and response
Question
dig infra.g6t.fr. NS
Answer
infra.g6t.fr. 5 NS ns2.globenet.org.
infra.g6t.fr. 5 NS ns1.globenet.org.
Authority
The response has no authority records.
Additional
ns1.globenet.org. 5 A 80.67.172.6
ns2.globenet.org. 5 A 91.224.148.239
ns1.globenet.org. 5 AAAA 2001:910:1401:0:0:0:0:6
ns2.globenet.org. 5 AAAA 2a03:7220:8080:ef00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0