Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-cn-53.cn. NS
Answer
awsdns-cn-53.cn. 5 NS g-ns-intl-114.awsdns-cn-53.cn.
awsdns-cn-53.cn. 5 NS g-ns-intl-3418.awsdns-cn-53.cn.
awsdns-cn-53.cn. 5 NS g-ns-2690.awsdns-cn-53.cn.
awsdns-cn-53.cn. 5 NS g-ns-114.awsdns-cn-53.cn.
awsdns-cn-53.cn. 5 NS g-ns-3418.awsdns-cn-53.cn.
awsdns-cn-53.cn. 5 NS g-ns-1091.awsdns-cn-53.cn.
Authority
The response has no authority records.
Additional
g-ns-114.awsdns-cn-53.cn. 5 A 52.82.176.114
g-ns-1091.awsdns-cn-53.cn. 5 A 52.82.180.67
g-ns-2690.awsdns-cn-53.cn. 5 A 54.222.34.130
g-ns-3418.awsdns-cn-53.cn. 5 A 54.222.37.90
g-ns-intl-114.awsdns-cn-53.cn. 5 A 52.46.184.114
g-ns-intl-3418.awsdns-cn-53.cn. 5 A 52.46.181.90
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0