Apex domains cannot have CNAME records.
Question and response
Question
dig tvujweb.net. NS
Answer
tvujweb.net. 5 NS ns.tvujweb.com.
tvujweb.net. 5 NS ns2.tvujweb.cz.
Authority
The response has no authority records.
Additional
ns.tvujweb.com. 5 A 168.119.180.52
ns2.tvujweb.cz. 5 A 109.123.220.5
ns.tvujweb.com. 5 AAAA 2a01:4f8:c013:cb5:0:0:0:1
ns2.tvujweb.cz. 5 AAAA 2001:1528:103:0:0:0:220:5
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0