Apex domains cannot have CNAME records.
Question and response
Question
dig s3-website.us-west-2.amazonaws.com. NS
Answer
s3-website.us-west-2.amazonaws.com. 5 NS ns-847.awsdns-41.net.
s3-website.us-west-2.amazonaws.com. 5 NS ns-160.awsdns-20.com.
s3-website.us-west-2.amazonaws.com. 5 NS ns-1678.awsdns-17.co.uk.
s3-website.us-west-2.amazonaws.com. 5 NS ns-1226.awsdns-25.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0