Apex domains cannot have CNAME records.
Question and response
Question
dig fr-par-2.baremetal.scw.cloud. NS
Answer
fr-par-2.baremetal.scw.cloud. 5 NS ns1.online.net.
fr-par-2.baremetal.scw.cloud. 5 NS ns0.online.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0