dns2.pwr.wroc.pl has no CNAME records.
Question and response
Question
dig dns2.pwr.wroc.pl. NS
Answer
The response has no answer records.
Authority
pwr.wroc.pl. 7200 SOA dns.pwr.wroc.pl. dns.pwr.edu.pl. 2026030402 10800 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0