Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-42.com. NS
Answer
awsdns-42.com. 5 NS g-ns-1770.awsdns-42.com.
awsdns-42.com. 5 NS g-ns-618.awsdns-42.com.
awsdns-42.com. 5 NS g-ns-43.awsdns-42.com.
awsdns-42.com. 5 NS g-ns-1194.awsdns-42.com.
Authority
The response has no authority records.
Additional
g-ns-43.awsdns-42.com. 5 A 205.251.192.43
g-ns-618.awsdns-42.com. 5 A 205.251.194.106
g-ns-1194.awsdns-42.com. 5 A 205.251.196.170
g-ns-1770.awsdns-42.com. 5 A 205.251.198.234
g-ns-43.awsdns-42.com. 5 AAAA 2600:9000:5300:2b00:0:0:0:1
g-ns-618.awsdns-42.com. 5 AAAA 2600:9000:5302:6a00:0:0:0:1
g-ns-1194.awsdns-42.com. 5 AAAA 2600:9000:5304:aa00:0:0:0:1
g-ns-1770.awsdns-42.com. 5 AAAA 2600:9000:5306:ea00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0