Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-25.org. NS
Answer
awsdns-25.org. 5 NS g-ns-153.awsdns-25.org.
awsdns-25.org. 5 NS g-ns-1625.awsdns-25.org.
awsdns-25.org. 5 NS g-ns-1052.awsdns-25.org.
awsdns-25.org. 5 NS g-ns-731.awsdns-25.org.
Authority
The response has no authority records.
Additional
g-ns-153.awsdns-25.org. 5 A 205.251.192.153
g-ns-731.awsdns-25.org. 5 A 205.251.194.219
g-ns-1052.awsdns-25.org. 5 A 205.251.196.28
g-ns-1625.awsdns-25.org. 5 A 205.251.198.89
g-ns-153.awsdns-25.org. 5 AAAA 2600:9000:5300:9900:0:0:0:1
g-ns-731.awsdns-25.org. 5 AAAA 2600:9000:5302:db00:0:0:0:1
g-ns-1052.awsdns-25.org. 5 AAAA 2600:9000:5304:1c00:0:0:0:1
g-ns-1625.awsdns-25.org. 5 AAAA 2600:9000:5306:5900:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0