Apex domains cannot have CNAME records.
Question and response
Question
dig ncs.com.sg. NS
Answer
ncs.com.sg. 5 NS ns-52.awsdns-06.com.
ncs.com.sg. 5 NS ns-1021.awsdns-63.net.
ncs.com.sg. 5 NS ns-1164.awsdns-17.org.
ncs.com.sg. 5 NS ns-1682.awsdns-18.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0