mx3.odn.de has no CNAME records.
Question and response
Question
dig mx3.odn.de. NS
Answer
The response has no answer records.
Authority
odn.de. 24 SOA dns1.odn.de. hostmaster.odn.de. 2026022500 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0