Apex domains cannot have CNAME records.
Question and response
Question
dig oxem23.net. NS
Answer
oxem23.net. 5 NS nssec.online.net.
oxem23.net. 5 NS ns.oxem23.net.
Authority
The response has no authority records.
Additional
ns.oxem23.net. 5 A 212.83.146.49
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0