Apex domains cannot have CNAME records.
Question and response
Question
dig awnet.cz. NS
Answer
awnet.cz. 5 NS ns1.awnet.cz.
Authority
The response has no authority records.
Additional
ns1.awnet.cz. 5 A 94.230.145.3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0