Apex domains cannot have CNAME records.
Question and response
Question
dig aws. NS
Answer
aws. 4 NS dns3.nic.aws.
aws. 4 NS dnsc.nic.aws.
aws. 4 NS dns1.nic.aws.
aws. 4 NS dns2.nic.aws.
aws. 4 NS dns4.nic.aws.
aws. 4 NS dnsb.nic.aws.
aws. 4 NS dnsa.nic.aws.
aws. 4 NS dnsd.nic.aws.
Authority
The response has no authority records.
Additional
dns1.nic.aws. 12806 A 213.248.218.53
dns2.nic.aws. 12806 A 103.49.82.53
dns3.nic.aws. 12806 A 213.248.222.53
dns4.nic.aws. 12806 A 43.230.50.53
dnsa.nic.aws. 12806 A 156.154.100.3
dnsb.nic.aws. 12806 A 156.154.101.3
dnsc.nic.aws. 12806 A 156.154.102.3
dnsd.nic.aws. 12806 A 156.154.103.3
dns1.nic.aws. 12806 AAAA 2a01:618:402:0:0:0:0:53
dns2.nic.aws. 12806 AAAA 2401:fd80:402:0:0:0:0:53
dns3.nic.aws. 12806 AAAA 2a01:618:406:0:0:0:0:53
dns4.nic.aws. 12806 AAAA 2401:fd80:406:0:0:0:0:53
dnsa.nic.aws. 12806 AAAA 2001:502:ad09:0:0:0:0:3
dnsb.nic.aws. 12806 AAAA 2001:502:2eda:0:0:0:0:3
dnsc.nic.aws. 12806 AAAA 2610:a1:1009:0:0:0:0:3
dnsd.nic.aws. 12806 AAAA 2610:a1:1010:0:0:0:0:3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0