Apex domains cannot have CNAME records.
Question and response
Question
dig s3-website.us-east-2.amazonaws.com. NS
Answer
s3-website.us-east-2.amazonaws.com. 5 NS ns-1206.awsdns-22.org.
s3-website.us-east-2.amazonaws.com. 5 NS ns-812.awsdns-37.net.
s3-website.us-east-2.amazonaws.com. 5 NS ns-485.awsdns-60.com.
s3-website.us-east-2.amazonaws.com. 5 NS ns-1918.awsdns-47.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0