Apex domains cannot have CNAME records.
Question and response
Question
dig entrem.fr. NS
Answer
entrem.fr. 5 NS ns4.safebrands.org.
entrem.fr. 5 NS ns1.safebrands.fr.
entrem.fr. 5 NS ns3.safebrands.com.
entrem.fr. 5 NS ns2.safebrands.eu.
entrem.fr. 5 NS ns5.safebrands.tech.
Authority
The response has no authority records.
Additional
ns1.safebrands.fr. 5 A 193.227.117.17
ns2.safebrands.eu. 5 A 194.50.187.18
ns3.safebrands.com. 5 A 194.0.182.19
ns4.safebrands.org. 5 A 193.227.117.20
ns5.safebrands.tech. 5 A 194.50.187.21
ns1.safebrands.fr. 5 AAAA 2a04:2b00:14cc:0:0:0:0:17
ns2.safebrands.eu. 5 AAAA 2a04:2b00:14dd:0:0:0:0:18
ns3.safebrands.com. 5 AAAA 2a04:2b00:14ee:0:0:0:0:19
ns4.safebrands.org. 5 AAAA 2a04:2b00:14cc:0:0:0:0:20
ns5.safebrands.tech. 5 AAAA 2a04:2b00:14dd:0:0:0:0:21
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0