Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-28.org. NS
Answer
awsdns-28.org. 5 NS g-ns-1628.awsdns-28.org.
awsdns-28.org. 5 NS g-ns-156.awsdns-28.org.
awsdns-28.org. 5 NS g-ns-734.awsdns-28.org.
awsdns-28.org. 5 NS g-ns-1055.awsdns-28.org.
Authority
The response has no authority records.
Additional
g-ns-156.awsdns-28.org. 5 A 205.251.192.156
g-ns-734.awsdns-28.org. 5 A 205.251.194.222
g-ns-1055.awsdns-28.org. 5 A 205.251.196.31
g-ns-1628.awsdns-28.org. 5 A 205.251.198.92
g-ns-156.awsdns-28.org. 5 AAAA 2600:9000:5300:9c00:0:0:0:1
g-ns-734.awsdns-28.org. 5 AAAA 2600:9000:5302:de00:0:0:0:1
g-ns-1055.awsdns-28.org. 5 AAAA 2600:9000:5304:1f00:0:0:0:1
g-ns-1628.awsdns-28.org. 5 AAAA 2600:9000:5306:5c00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0