Apex domains cannot have CNAME records.
Question and response
Question
dig amibit.si. NS
Answer
amibit.si. 2 NS ns1.amibit.si.
amibit.si. 2 NS ns2.amibit.si.
Authority
The response has no authority records.
Additional
ns1.amibit.si. 1 A 193.9.21.45
ns2.amibit.si. 1 A 5.32.143.53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0