Apex domains cannot have CNAME records.
Question and response
Question
dig okay.pl. NS
Answer
okay.pl. 5 NS ns80.zetosa.com.pl.
okay.pl. 5 NS zetosak80.zetosa.com.pl.
Authority
The response has no authority records.
Additional
ns80.zetosa.com.pl. 5 A 80.85.224.2
zetosak80.zetosa.com.pl. 5 A 80.85.224.50
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0