ns1.ntdns.de has no CNAME records.
Question and response
Question
dig ns1.ntdns.de. NS
Answer
The response has no answer records.
Authority
ntdns.de. 183 SOA ns1.ntdns.de. hostmaster.fastit.net. 2023011202 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0