dns.iwelt-ag.net has no CNAME records.
Question and response
Question
dig dns.iwelt-ag.net. NS
Answer
The response has no answer records.
Authority
iwelt-ag.net. 191 SOA dns.iwelt-ag.net. domainmaster.iwelt-ag.net. 2026021701 43200 3600 2419200 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0