Apex domains cannot have CNAME records.
Question and response
Question
dig pe3ny.net. NS
Answer
pe3ny.net. 5 NS ns.pe3ny.net.
pe3ny.net. 5 NS bt.satoya.cz.
Authority
The response has no authority records.
Additional
bt.satoya.cz. 5 A 212.24.129.94
ns.pe3ny.net. 5 A 94.142.233.50
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0