isp.pttk.pl has no CNAME records.
Question and response
Question
dig isp.pttk.pl. NS
Answer
The response has no answer records.
Authority
pttk.pl. 267 SOA ns0.pttk.pl. root.pttk.pl. 2024101002 604800 86400 2419200 1500
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0