Apex domains cannot have CNAME records.
Question and response
Question
dig awsglobalaccelerator.com. NS
Answer
awsglobalaccelerator.com. 5 NS ns-609.awsdns-12.net.
awsglobalaccelerator.com. 5 NS ns-409.awsdns-51.com.
awsglobalaccelerator.com. 5 NS ns-1949.awsdns-51.co.uk.
awsglobalaccelerator.com. 5 NS ns-1484.awsdns-57.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0