Apex domains cannot have CNAME records.
Question and response
Question
dig af-south-1.compute.amazonaws.com. NS
Answer
af-south-1.compute.amazonaws.com. 5 NS ns-276.awsdns-34.com.
af-south-1.compute.amazonaws.com. 5 NS ns-1109.awsdns-10.org.
af-south-1.compute.amazonaws.com. 5 NS ns-817.awsdns-38.net.
af-south-1.compute.amazonaws.com. 5 NS ns-1647.awsdns-13.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0