mx.rozhled.net has no CNAME records.
Question and response
Question
dig mx.rozhled.net. NS
Answer
The response has no answer records.
Authority
rozhled.net. 600 SOA ns.rozhled.cz. admin.rozhled.cz. 2025093000 3600 900 1209600 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0