Apex domains cannot have CNAME records.
Question and response
Question
dig perfect.net.pl. NS
Answer
perfect.net.pl. 5 NS ns1.perfect-net.pl.
perfect.net.pl. 5 NS dns.iweb.pl.
perfect.net.pl. 5 NS dns.wolfnet.pl.
Authority
The response has no authority records.
Additional
dns.iweb.pl. 5 A 212.122.221.129
dns.wolfnet.pl. 5 A 62.181.8.176
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0