Apex domains cannot have CNAME records.
Question and response
Question
dig cntcloud.com. NS
Answer
cntcloud.com. 2 NS ns21.domaincontrol.com.
cntcloud.com. 2 NS ns22.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0