mail.interrisk.de has no CNAME records.
Question and response
Question
dig mail.interrisk.de. NS
Answer
The response has no answer records.
Authority
interrisk.de. 15 SOA ns.vistec.net. root.ns.vistec.net. 2025121606 86400 14400 1209600 100
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0