mail2.fuw.edu.pl has no CNAME records.
Question and response
Question
dig mail2.fuw.edu.pl. NS
Answer
The response has no answer records.
Authority
fuw.edu.pl. 360 SOA dns.fuw.edu.pl. hostmaster.fuw.edu.pl. 2026030300 7200 7200 604800 360
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0