Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-16.com. NS
Answer
awsdns-16.com. 5 NS g-ns-1744.awsdns-16.com.
awsdns-16.com. 5 NS g-ns-592.awsdns-16.com.
awsdns-16.com. 5 NS g-ns-17.awsdns-16.com.
awsdns-16.com. 5 NS g-ns-1168.awsdns-16.com.
Authority
The response has no authority records.
Additional
g-ns-17.awsdns-16.com. 5 A 205.251.192.17
g-ns-592.awsdns-16.com. 5 A 205.251.194.80
g-ns-1168.awsdns-16.com. 5 A 205.251.196.144
g-ns-1744.awsdns-16.com. 5 A 205.251.198.208
g-ns-17.awsdns-16.com. 5 AAAA 2600:9000:5300:1100:0:0:0:1
g-ns-592.awsdns-16.com. 5 AAAA 2600:9000:5302:5000:0:0:0:1
g-ns-1168.awsdns-16.com. 5 AAAA 2600:9000:5304:9000:0:0:0:1
g-ns-1744.awsdns-16.com. 5 AAAA 2600:9000:5306:d000:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0