mailproxy.netzwerge.de has no CNAME records.
Question and response
Question
dig mailproxy.netzwerge.de. NS
Answer
The response has no answer records.
Authority
netzwerge.de. 115 SOA ns1.netzwerge.de. hostmaster.netzwerge.de. 2025021297 28800 7200 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0