Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-19.com. NS
Answer
awsdns-19.com. 5 NS g-ns-595.awsdns-19.com.
awsdns-19.com. 5 NS g-ns-1747.awsdns-19.com.
awsdns-19.com. 5 NS g-ns-20.awsdns-19.com.
awsdns-19.com. 5 NS g-ns-1171.awsdns-19.com.
Authority
The response has no authority records.
Additional
g-ns-20.awsdns-19.com. 5 A 205.251.192.20
g-ns-595.awsdns-19.com. 5 A 205.251.194.83
g-ns-1171.awsdns-19.com. 5 A 205.251.196.147
g-ns-1747.awsdns-19.com. 5 A 205.251.198.211
g-ns-20.awsdns-19.com. 5 AAAA 2600:9000:5300:1400:0:0:0:1
g-ns-595.awsdns-19.com. 5 AAAA 2600:9000:5302:5300:0:0:0:1
g-ns-1171.awsdns-19.com. 5 AAAA 2600:9000:5304:9300:0:0:0:1
g-ns-1747.awsdns-19.com. 5 AAAA 2600:9000:5306:d300:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0