Apex domains cannot have CNAME records.
Question and response
Question
dig cyberville.com.sg. NS
Answer
cyberville.com.sg. 5 NS eoin.ns.cloudflare.com.
cyberville.com.sg. 5 NS sierra.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0