Apex domains cannot have CNAME records.
Question and response
Question
dig s3-website.ca-central-1.amazonaws.com. NS
Answer
s3-website.ca-central-1.amazonaws.com. 5 NS ns-1266.awsdns-30.org.
s3-website.ca-central-1.amazonaws.com. 5 NS ns-716.awsdns-25.net.
s3-website.ca-central-1.amazonaws.com. 5 NS ns-146.awsdns-18.com.
s3-website.ca-central-1.amazonaws.com. 5 NS ns-1541.awsdns-00.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0