dns.amu.edu.pl has no CNAME records.
Question and response
Question
dig dns.amu.edu.pl. NS
Answer
The response has no answer records.
Authority
amu.edu.pl. 1889 SOA dns.amu.edu.pl. dnsadm.amu.edu.pl. 2026012030 43200 3600 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0