Apex domains cannot have CNAME records.
Question and response
Question
dig oxemis.net. NS
Answer
oxemis.net. 5 NS sdns2.ovh.net.
oxemis.net. 5 NS ns.oxemis.net.
Authority
The response has no authority records.
Additional
ns.oxemis.net. 5 A 51.254.21.233
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0