Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-15.org. NS
Answer
awsdns-15.org. 5 NS g-ns-143.awsdns-15.org.
awsdns-15.org. 5 NS g-ns-1042.awsdns-15.org.
awsdns-15.org. 5 NS g-ns-721.awsdns-15.org.
awsdns-15.org. 5 NS g-ns-1615.awsdns-15.org.
Authority
The response has no authority records.
Additional
g-ns-143.awsdns-15.org. 5 A 205.251.192.143
g-ns-721.awsdns-15.org. 5 A 205.251.194.209
g-ns-1042.awsdns-15.org. 5 A 205.251.196.18
g-ns-1615.awsdns-15.org. 5 A 205.251.198.79
g-ns-143.awsdns-15.org. 5 AAAA 2600:9000:5300:8f00:0:0:0:1
g-ns-721.awsdns-15.org. 5 AAAA 2600:9000:5302:d100:0:0:0:1
g-ns-1042.awsdns-15.org. 5 AAAA 2600:9000:5304:1200:0:0:0:1
g-ns-1615.awsdns-15.org. 5 AAAA 2600:9000:5306:4f00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0