mx20.vwgroup.com has no CNAME records.
Question and response
Question
dig mx20.vwgroup.com. NS
Answer
The response has no answer records.
Authority
vwgroup.com. 4870 SOA ns1.volkswagen.de. dns.volkswagen.de. 2021082399 86400 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0