Apex domains cannot have CNAME records.
Question and response
Question
dig ocx.dk. NS
Answer
ocx.dk. 5 NS dan.ns.cloudflare.com.
ocx.dk. 5 NS mary.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0