mx2.in-berlin.de has no CNAME records.
Question and response
Question
dig mx2.in-berlin.de. NS
Answer
The response has no answer records.
Authority
in-berlin.de. 900 SOA ns1.in-berlin.de. domain.in-berlin.de. 2026022418 21600 1800 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0