Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-29.org. NS
Answer
awsdns-29.org. 5 NS g-ns-1056.awsdns-29.org.
awsdns-29.org. 5 NS g-ns-157.awsdns-29.org.
awsdns-29.org. 5 NS g-ns-735.awsdns-29.org.
awsdns-29.org. 5 NS g-ns-1629.awsdns-29.org.
Authority
The response has no authority records.
Additional
g-ns-157.awsdns-29.org. 5 A 205.251.192.157
g-ns-735.awsdns-29.org. 5 A 205.251.194.223
g-ns-1056.awsdns-29.org. 5 A 205.251.196.32
g-ns-1629.awsdns-29.org. 5 A 205.251.198.93
g-ns-157.awsdns-29.org. 5 AAAA 2600:9000:5300:9d00:0:0:0:1
g-ns-735.awsdns-29.org. 5 AAAA 2600:9000:5302:df00:0:0:0:1
g-ns-1056.awsdns-29.org. 5 AAAA 2600:9000:5304:2000:0:0:0:1
g-ns-1629.awsdns-29.org. 5 AAAA 2600:9000:5306:5d00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0