Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-33.com. NS
Answer
awsdns-33.com. 5 NS g-ns-609.awsdns-33.com.
awsdns-33.com. 5 NS g-ns-34.awsdns-33.com.
awsdns-33.com. 5 NS g-ns-1761.awsdns-33.com.
awsdns-33.com. 5 NS g-ns-1185.awsdns-33.com.
Authority
The response has no authority records.
Additional
g-ns-34.awsdns-33.com. 5 A 205.251.192.34
g-ns-609.awsdns-33.com. 5 A 205.251.194.97
g-ns-1185.awsdns-33.com. 5 A 205.251.196.161
g-ns-1761.awsdns-33.com. 5 A 205.251.198.225
g-ns-34.awsdns-33.com. 5 AAAA 2600:9000:5300:2200:0:0:0:1
g-ns-609.awsdns-33.com. 5 AAAA 2600:9000:5302:6100:0:0:0:1
g-ns-1185.awsdns-33.com. 5 AAAA 2600:9000:5304:a100:0:0:0:1
g-ns-1761.awsdns-33.com. 5 AAAA 2600:9000:5306:e100:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0