mail.v-dns.de has no CNAME records.
Question and response
Question
dig mail.v-dns.de. NS
Answer
The response has no answer records.
Authority
v-dns.de. 57115 SOA ns01.v-dns.de. hostmaster.v-dns.de. 2024124833 14400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0