Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-48.com. NS
Answer
awsdns-48.com. 5 NS g-ns-49.awsdns-48.com.
awsdns-48.com. 5 NS g-ns-624.awsdns-48.com.
awsdns-48.com. 5 NS g-ns-1200.awsdns-48.com.
awsdns-48.com. 5 NS g-ns-1776.awsdns-48.com.
Authority
The response has no authority records.
Additional
g-ns-49.awsdns-48.com. 5 A 205.251.192.49
g-ns-624.awsdns-48.com. 5 A 205.251.194.112
g-ns-1200.awsdns-48.com. 5 A 205.251.196.176
g-ns-1776.awsdns-48.com. 5 A 205.251.198.240
g-ns-49.awsdns-48.com. 5 AAAA 2600:9000:5300:3100:0:0:0:1
g-ns-624.awsdns-48.com. 5 AAAA 2600:9000:5302:7000:0:0:0:1
g-ns-1200.awsdns-48.com. 5 AAAA 2600:9000:5304:b000:0:0:0:1
g-ns-1776.awsdns-48.com. 5 AAAA 2600:9000:5306:f000:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0