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-1922.awsdns-48.co.uk.
s3-website-us-west-2.amazonaws.com. 5 NS ns-1470.awsdns-55.org.
s3-website-us-west-2.amazonaws.com. 5 NS ns-364.awsdns-45.com.
s3-website-us-west-2.amazonaws.com. 5 NS ns-641.awsdns-16.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0