Apex domains cannot have CNAME records.
Question and response
Question
dig ap-east-1.compute.amazonaws.com. NS
Answer
ap-east-1.compute.amazonaws.com. 5 NS ns-465.awsdns-58.com.
ap-east-1.compute.amazonaws.com. 5 NS ns-1951.awsdns-51.co.uk.
ap-east-1.compute.amazonaws.com. 5 NS ns-1491.awsdns-58.org.
ap-east-1.compute.amazonaws.com. 5 NS ns-548.awsdns-04.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0