ns2.zenbox.pl has no CNAME records.
Question and response
Question
dig ns2.zenbox.pl. NS
Answer
The response has no answer records.
Authority
zenbox.pl. 96 SOA ns1.zenbox.pl. hostmaster.zenbox.pl. 2026012800 600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0