Apex domains cannot have CNAME records.
Question and response
Question
dig czechproject.cz. NS
Answer
czechproject.cz. 1 NS ns.profiwh.com.
czechproject.cz. 1 NS ns.profiwh.cz.
czechproject.cz. 1 NS ns.profiwh.info.
czechproject.cz. 1 NS ns.profiwh.net.
Authority
The response has no authority records.
Additional
ns.profiwh.cz. 1 A 31.31.75.42
ns.profiwh.com. 1 A 94.113.246.20
ns.profiwh.net. 1 A 85.93.166.254
ns.profiwh.info. 1 A 212.80.67.190
ns.profiwh.cz. 1 AAAA 2a02:2b88:2:1:0:0:39c2:1
ns.profiwh.com. 1 AAAA 2a02:8304:1:6:0:0:246:20
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0