Apex domains cannot have CNAME records.
Question and response
Question
dig s3-fips-r-w.ca-central-1.amazonaws.com. NS
Answer
s3-fips-r-w.ca-central-1.amazonaws.com. 5 NS ns-1117.awsdns-11.org.
s3-fips-r-w.ca-central-1.amazonaws.com. 5 NS ns-874.awsdns-45.net.
s3-fips-r-w.ca-central-1.amazonaws.com. 5 NS ns-425.awsdns-53.com.
s3-fips-r-w.ca-central-1.amazonaws.com. 5 NS ns-1863.awsdns-40.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0