mx.bahnhof.net has no CNAME records.
Question and response
Question
dig mx.bahnhof.net. NS
Answer
The response has no answer records.
Authority
bahnhof.net. 300 SOA ns.bahnhof.se. hostmaster.bahnhof.net. 2026022506 1800 600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0