ns2.netium.pl has no CNAME records.
Question and response
Question
dig ns2.netium.pl. NS
Answer
The response has no answer records.
Authority
netium.pl. 10800 SOA ns1.netium.pl. info.netium.pl. 2020112126 86400 86400 2592000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0