Apex domains cannot have CNAME records.
Question and response
Question
dig hti.pl. NS
Answer
hti.pl. 5 NS dns0.hti.pl.
hti.pl. 5 NS dns1.hti.pl.
Authority
The response has no authority records.
Additional
dns0.hti.pl. 5 A 217.168.128.21
dns1.hti.pl. 5 A 217.168.128.121
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0