Apex domains cannot have CNAME records.
Question and response
Question
dig uakom.sk. NS
Answer
uakom.sk. 5 NS ns.fei.stuba.sk.
uakom.sk. 5 NS ans.uakom.sk.
uakom.sk. 5 NS sun.uakom.sk.
Authority
The response has no authority records.
Additional
ns.fei.stuba.sk. 5 A 147.175.111.15
ans.uakom.sk. 5 A 194.160.185.188
sun.uakom.sk. 5 A 192.108.131.11
ns.fei.stuba.sk. 5 AAAA 2001:4118:10:6f00:0:0:0:f
ans.uakom.sk. 5 AAAA 2001:4118:100:c:0:0:0:188
sun.uakom.sk. 5 AAAA 2001:4118:100:1:0:0:0:11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0