Apex domains cannot have CNAME records.
Question and response
Question
dig xemis.net. NS
Answer
xemis.net. 1 NS ns.xemis.net.
xemis.net. 1 NS sdns2.ovh.net.
Authority
The response has no authority records.
Additional
ns.xemis.net. 1 A 176.31.206.131
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0