Apex domains cannot have CNAME records.
Question and response
Question
dig leon.com.pl. NS
Answer
leon.com.pl. 5 NS ns2.leon.pl.
leon.com.pl. 5 NS ns1.leon.pl.
Authority
The response has no authority records.
Additional
ns1.leon.pl. 5 A 195.3.203.2
ns2.leon.pl. 5 A 195.66.73.10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0