Apex domains cannot have CNAME records.
Question and response
Question
dig barbuchu.com. NS
Answer
barbuchu.com. 4 NS ns2.la-boite.com.
barbuchu.com. 4 NS ns1.la-boite.com.
Authority
The response has no authority records.
Additional
ns1.la-boite.com. 4 A 212.83.158.214
ns2.la-boite.com. 4 A 151.80.66.145
ns2.la-boite.com. 4 AAAA 2001:41d0:1008:c13:0:0:0:145
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0