Apex domains cannot have CNAME records.
Question and response
Question
dig amzndns.org. NS
Answer
amzndns.org. 5 NS g-ns2.amzndns.org.
amzndns.org. 5 NS g-ns4.amzndns.org.
amzndns.org. 5 NS g-ns1.amzndns.org.
amzndns.org. 5 NS g-ns3.amzndns.org.
Authority
The response has no authority records.
Additional
g-ns1.amzndns.org. 5 A 205.251.197.130
g-ns2.amzndns.org. 5 A 205.251.195.43
g-ns3.amzndns.org. 5 A 205.251.199.169
g-ns4.amzndns.org. 5 A 205.251.193.37
g-ns1.amzndns.org. 5 AAAA 2600:9000:5305:8200:0:0:0:1
g-ns2.amzndns.org. 5 AAAA 2600:9000:5303:2b00:0:0:0:1
g-ns3.amzndns.org. 5 AAAA 2600:9000:5307:a900:0:0:0:1
g-ns4.amzndns.org. 5 AAAA 2600:9000:5301:2500:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0