Apex domains cannot have CNAME records.
Question and response
Question
dig intern1.dk. NS
Answer
intern1.dk. 1 NS ns3.pil.dk.
intern1.dk. 1 NS ns1.pil.dk.
intern1.dk. 1 NS ns2.pil.dk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0