Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-29.net. NS
Answer
awsdns-29.net. 5 NS g-ns-478.awsdns-29.net.
awsdns-29.net. 5 NS g-ns-799.awsdns-29.net.
awsdns-29.net. 5 NS g-ns-1373.awsdns-29.net.
awsdns-29.net. 5 NS g-ns-1949.awsdns-29.net.
Authority
The response has no authority records.
Additional
g-ns-478.awsdns-29.net. 5 A 205.251.193.222
g-ns-799.awsdns-29.net. 5 A 205.251.195.31
g-ns-1373.awsdns-29.net. 5 A 205.251.197.93
g-ns-1949.awsdns-29.net. 5 A 205.251.199.157
g-ns-478.awsdns-29.net. 5 AAAA 2600:9000:5301:de00:0:0:0:1
g-ns-799.awsdns-29.net. 5 AAAA 2600:9000:5303:1f00:0:0:0:1
g-ns-1373.awsdns-29.net. 5 AAAA 2600:9000:5305:5d00:0:0:0:1
g-ns-1949.awsdns-29.net. 5 AAAA 2600:9000:5307:9d00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0