Apex domains cannot have CNAME records.
Question and response
Question
dig szikula.com. NS
Answer
szikula.com. 5 NS ns1.szikula.com.
szikula.com. 5 NS ns2.szikula.com.
Authority
The response has no authority records.
Additional
ns1.szikula.com. 5 A 103.249.31.4
ns2.szikula.com. 5 A 103.249.31.10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0