Apex domains cannot have CNAME records.
Question and response
Question
dig us-east-2.amazonses.com. NS
Answer
us-east-2.amazonses.com. 5 NS ns-1187.awsdns-20.org.
us-east-2.amazonses.com. 5 NS ns-937.awsdns-53.net.
us-east-2.amazonses.com. 5 NS ns-112.awsdns-14.com.
us-east-2.amazonses.com. 5 NS ns-1681.awsdns-18.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0