Apex domains cannot have CNAME records.
Question and response
Question
dig karas.si. NS
Answer
karas.si. 2 NS rns4.neoserv.si.
karas.si. 2 NS rns3.neoserv.si.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0