Apex domains cannot have CNAME records.
Question and response
Question
dig ctzgchina.org. NS
Answer
ctzgchina.org. 5 NS ns-107.awsdns-13.com.
ctzgchina.org. 5 NS ns-1995.awsdns-57.co.uk.
ctzgchina.org. 5 NS ns-1142.awsdns-14.org.
ctzgchina.org. 5 NS ns-168.awsdns-21.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0