Apex domains cannot have CNAME records.
Question and response
Question
dig onead.com.tw. NS
Answer
onead.com.tw. 1 NS ns-cloud2.googledomains.com.
onead.com.tw. 1 NS ns-cloud4.googledomains.com.
onead.com.tw. 1 NS ns-cloud1.googledomains.com.
onead.com.tw. 1 NS ns-cloud3.googledomains.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0