mail.mijndnsserver.net has no CNAME records.
Question and response
Question
dig mail.mijndnsserver.net. NS
Answer
The response has no answer records.
Authority
mijndnsserver.net. 4474 SOA ns1.mijndnsserver.nl. hostmaster.mijndnsserver.net. 2025032601 28800 7200 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0