Apex domains cannot have CNAME records.
Question and response
Question
dig provector.pl. NS
Answer
provector.pl. 5 NS dns2.provector.pl.
provector.pl. 5 NS dns1.provector.pl.
Authority
The response has no authority records.
Additional
dns1.provector.pl. 5 A 93.175.129.10
dns2.provector.pl. 5 A 93.175.129.11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0