Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-cn-17.cn. NS
Answer
awsdns-cn-17.cn. 5 NS g-ns-2368.awsdns-cn-17.cn.
awsdns-cn-17.cn. 5 NS g-ns-1915.awsdns-cn-17.cn.
awsdns-cn-17.cn. 5 NS g-ns-590.awsdns-cn-17.cn.
awsdns-cn-17.cn. 5 NS g-ns-intl-3380.awsdns-cn-17.cn.
awsdns-cn-17.cn. 5 NS g-ns-intl-590.awsdns-cn-17.cn.
awsdns-cn-17.cn. 5 NS g-ns-3380.awsdns-cn-17.cn.
Authority
The response has no authority records.
Additional
g-ns-590.awsdns-cn-17.cn. 5 A 52.82.178.78
g-ns-1915.awsdns-cn-17.cn. 5 A 52.82.183.123
g-ns-2368.awsdns-cn-17.cn. 5 A 54.222.33.64
g-ns-3380.awsdns-cn-17.cn. 5 A 54.222.37.52
g-ns-intl-590.awsdns-cn-17.cn. 5 A 52.46.186.78
g-ns-intl-3380.awsdns-cn-17.cn. 5 A 52.46.181.52
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0