ns2.domena.pl has no CNAME records.
Question and response
Question
dig ns2.domena.pl. NS
Answer
The response has no answer records.
Authority
domena.pl. 8159 SOA ns1.domena.pl. bok.domena.pl. 2007064083 7200 1800 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0