mail.ediscom.net has no CNAME records.
Question and response
Question
dig mail.ediscom.net. NS
Answer
The response has no answer records.
Authority
ediscom.net. 2380 SOA ns3.ediscom.de. zonemaster.ediscom.de. 2019040914 28800 7200 604800 28800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0