auth05.ns.tdc.net has no CNAME records.
Question and response
Question
dig auth05.ns.tdc.net. NS
Answer
The response has no answer records.
Authority
tdc.net. 2990 SOA auth01.ns.tele.dk. dns.eng.tdc.net. 2024050701 7200 1800 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0