Apex domains cannot have CNAME records.
Question and response
Question
dig us-west-1.compute.amazonaws.com. NS
Answer
us-west-1.compute.amazonaws.com. 5 NS ns-1874.awsdns-42.co.uk.
us-west-1.compute.amazonaws.com. 5 NS ns-519.awsdns-00.net.
us-west-1.compute.amazonaws.com. 5 NS ns-80.awsdns-10.com.
us-west-1.compute.amazonaws.com. 5 NS ns-1320.awsdns-37.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0