Apex domains cannot have CNAME records.
Question and response
Question
dig s3.us-east-2.amazonaws.com. NS
Answer
s3.us-east-2.amazonaws.com. 5 NS ns-983.awsdns-58.net.
s3.us-east-2.amazonaws.com. 5 NS ns-1819.awsdns-35.co.uk.
s3.us-east-2.amazonaws.com. 5 NS ns-296.awsdns-37.com.
s3.us-east-2.amazonaws.com. 5 NS ns-1093.awsdns-08.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0