Apex domains cannot have CNAME records.
Question and response
Question
dig mhhosting.dk. NS
Answer
mhhosting.dk. 5 NS DNS01.mhhosting.dk.
mhhosting.dk. 5 NS DNS02.mhhosting.dk.
mhhosting.dk. 5 NS DNS03.mhhosting.dk.
Authority
The response has no authority records.
Additional
dns01.mhhosting.dk. 5 A 188.180.76.248
dns02.mhhosting.dk. 5 A 188.180.76.244
dns03.mhhosting.dk. 5 A 2.108.64.134
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0