Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-13.org. NS
Answer
awsdns-13.org. 5 NS g-ns-141.awsdns-13.org.
awsdns-13.org. 5 NS g-ns-719.awsdns-13.org.
awsdns-13.org. 5 NS g-ns-1040.awsdns-13.org.
awsdns-13.org. 5 NS g-ns-1613.awsdns-13.org.
Authority
The response has no authority records.
Additional
g-ns-141.awsdns-13.org. 5 A 205.251.192.141
g-ns-719.awsdns-13.org. 5 A 205.251.194.207
g-ns-1040.awsdns-13.org. 5 A 205.251.196.16
g-ns-1613.awsdns-13.org. 5 A 205.251.198.77
g-ns-141.awsdns-13.org. 5 AAAA 2600:9000:5300:8d00:0:0:0:1
g-ns-719.awsdns-13.org. 5 AAAA 2600:9000:5302:cf00:0:0:0:1
g-ns-1040.awsdns-13.org. 5 AAAA 2600:9000:5304:1000:0:0:0:1
g-ns-1613.awsdns-13.org. 5 AAAA 2600:9000:5306:4d00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0