Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-27.com. NS
Answer
awsdns-27.com. 1 NS g-ns-1755.awsdns-27.com.
awsdns-27.com. 1 NS g-ns-28.awsdns-27.com.
awsdns-27.com. 1 NS g-ns-603.awsdns-27.com.
awsdns-27.com. 1 NS g-ns-1179.awsdns-27.com.
Authority
The response has no authority records.
Additional
g-ns-28.awsdns-27.com. 1 A 205.251.192.28
g-ns-603.awsdns-27.com. 1 A 205.251.194.91
g-ns-1179.awsdns-27.com. 1 A 205.251.196.155
g-ns-1755.awsdns-27.com. 1 A 205.251.198.219
g-ns-28.awsdns-27.com. 1 AAAA 2600:9000:5300:1c00:0:0:0:1
g-ns-603.awsdns-27.com. 1 AAAA 2600:9000:5302:5b00:0:0:0:1
g-ns-1179.awsdns-27.com. 1 AAAA 2600:9000:5304:9b00:0:0:0:1
g-ns-1755.awsdns-27.com. 1 AAAA 2600:9000:5306:db00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0