ns1.dnsservers.dk has no CNAME records.
Question and response
Question
dig ns1.dnsservers.dk. NS
Answer
The response has no answer records.
Authority
dnsservers.dk. 2635 SOA ns2.dnsservers.dk. hostmaster.dnsservers.dk. 2025072401 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0