Apex domains cannot have CNAME records.
Question and response
Question
dig toya.net.pl. NS
Answer
toya.net.pl. 5 NS dns2.atman.pl.
toya.net.pl. 5 NS dns.toya.net.pl.
Authority
The response has no authority records.
Additional
dns.toya.net.pl. 5 A 217.113.224.13
dns2.atman.pl. 4 A 77.79.235.102
dns2.atman.pl. 4 AAAA 2001:1a68:0:0:0:0:4d4f:eb66
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0