Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-31.org. NS
Answer
awsdns-31.org. 4 NS g-ns-1058.awsdns-31.org.
awsdns-31.org. 4 NS g-ns-159.awsdns-31.org.
awsdns-31.org. 4 NS g-ns-737.awsdns-31.org.
awsdns-31.org. 4 NS g-ns-1631.awsdns-31.org.
Authority
The response has no authority records.
Additional
g-ns-159.awsdns-31.org. 4 A 205.251.192.159
g-ns-737.awsdns-31.org. 4 A 205.251.194.225
g-ns-1058.awsdns-31.org. 4 A 205.251.196.34
g-ns-1631.awsdns-31.org. 4 A 205.251.198.95
g-ns-159.awsdns-31.org. 4 AAAA 2600:9000:5300:9f00:0:0:0:1
g-ns-737.awsdns-31.org. 4 AAAA 2600:9000:5302:e100:0:0:0:1
g-ns-1058.awsdns-31.org. 4 AAAA 2600:9000:5304:2200:0:0:0:1
g-ns-1631.awsdns-31.org. 4 AAAA 2600:9000:5306:5f00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0