Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-cn-19.cn. NS
Answer
awsdns-cn-19.cn. 1 NS g-ns-2421.awsdns-cn-19.cn.
awsdns-cn-19.cn. 1 NS g-ns-intl-3570.awsdns-cn-19.cn.
awsdns-cn-19.cn. 1 NS g-ns-intl-895.awsdns-cn-19.cn.
awsdns-cn-19.cn. 1 NS g-ns-1747.awsdns-cn-19.cn.
awsdns-cn-19.cn. 1 NS g-ns-895.awsdns-cn-19.cn.
awsdns-cn-19.cn. 1 NS g-ns-3570.awsdns-cn-19.cn.
Authority
The response has no authority records.
Additional
g-ns-895.awsdns-cn-19.cn. 1 A 52.82.179.127
g-ns-1747.awsdns-cn-19.cn. 1 A 52.82.182.211
g-ns-2421.awsdns-cn-19.cn. 1 A 54.222.33.117
g-ns-3570.awsdns-cn-19.cn. 1 A 54.222.37.242
g-ns-intl-895.awsdns-cn-19.cn. 1 A 52.46.187.127
g-ns-intl-3570.awsdns-cn-19.cn. 1 A 52.46.181.242
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0