mail2.drberndsen.de has no CNAME records.
Question and response
Question
dig mail2.drberndsen.de. NS
Answer
The response has no answer records.
Authority
drberndsen.de. 5051 SOA root-dns.netcup.net. dnsadmin.netcup.net. 2025110347 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0