dns1.dtu.dk has no CNAME records.
Question and response
Question
dig dns1.dtu.dk. NS
Answer
The response has no answer records.
Authority
dtu.dk. 195 SOA ait-pibgm01.win.dtu.dk. dnsadmin.dtu.dk. 2022100836 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0