Apex domains cannot have CNAME records.
Question and response
Question
dig s3-deprecated.ca-central-1.amazonaws.com. NS
Answer
s3-deprecated.ca-central-1.amazonaws.com. 4 NS ns-68.awsdns-08.com.
s3-deprecated.ca-central-1.amazonaws.com. 4 NS ns-566.awsdns-06.net.
s3-deprecated.ca-central-1.amazonaws.com. 4 NS ns-1383.awsdns-44.org.
s3-deprecated.ca-central-1.amazonaws.com. 4 NS ns-1972.awsdns-54.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0