dns2.jettel.pl has no CNAME records.
Question and response
Question
dig dns2.jettel.pl. NS
Answer
The response has no answer records.
Authority
jettel.pl. 3571 SOA ns2.tld.pl. admin.tld.pl. 2018110602 10800 1800 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0