Apex domains cannot have CNAME records.
Question and response
Question
dig us-west-2.amazonaws.com. NS
Answer
us-west-2.amazonaws.com. 5 NS ns-156.awsdns-19.com.
us-west-2.amazonaws.com. 5 NS ns-1556.awsdns-02.co.uk.
us-west-2.amazonaws.com. 5 NS ns-1522.awsdns-62.org.
us-west-2.amazonaws.com. 5 NS ns-821.awsdns-38.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0