Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-55.com. NS
Answer
awsdns-55.com. 5 NS g-ns-631.awsdns-55.com.
awsdns-55.com. 5 NS g-ns-1207.awsdns-55.com.
awsdns-55.com. 5 NS g-ns-1783.awsdns-55.com.
awsdns-55.com. 5 NS g-ns-56.awsdns-55.com.
Authority
The response has no authority records.
Additional
g-ns-56.awsdns-55.com. 5 A 205.251.192.56
g-ns-631.awsdns-55.com. 5 A 205.251.194.119
g-ns-1207.awsdns-55.com. 5 A 205.251.196.183
g-ns-1783.awsdns-55.com. 5 A 205.251.198.247
g-ns-56.awsdns-55.com. 5 AAAA 2600:9000:5300:3800:0:0:0:1
g-ns-631.awsdns-55.com. 5 AAAA 2600:9000:5302:7700:0:0:0:1
g-ns-1207.awsdns-55.com. 5 AAAA 2600:9000:5304:b700:0:0:0:1
g-ns-1783.awsdns-55.com. 5 AAAA 2600:9000:5306:f700:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0