Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-50.com. NS
Answer
awsdns-50.com. 5 NS g-ns-51.awsdns-50.com.
awsdns-50.com. 5 NS g-ns-626.awsdns-50.com.
awsdns-50.com. 5 NS g-ns-1202.awsdns-50.com.
awsdns-50.com. 5 NS g-ns-1778.awsdns-50.com.
Authority
The response has no authority records.
Additional
g-ns-51.awsdns-50.com. 5 A 205.251.192.51
g-ns-626.awsdns-50.com. 5 A 205.251.194.114
g-ns-1202.awsdns-50.com. 5 A 205.251.196.178
g-ns-1778.awsdns-50.com. 5 A 205.251.198.242
g-ns-51.awsdns-50.com. 5 AAAA 2600:9000:5300:3300:0:0:0:1
g-ns-626.awsdns-50.com. 5 AAAA 2600:9000:5302:7200:0:0:0:1
g-ns-1202.awsdns-50.com. 5 AAAA 2600:9000:5304:b200:0:0:0:1
g-ns-1778.awsdns-50.com. 5 AAAA 2600:9000:5306:f200:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0