mail.cloudmonit.pl has no CNAME records.
Question and response
Question
dig mail.cloudmonit.pl. NS
Answer
The response has no answer records.
Authority
cloudmonit.pl. 466 SOA ns1.monit24.pl. dns.monit24.pl. 2022042001 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0