Apex domains cannot have CNAME records.
Question and response
Question
dig apol.com.tw. NS
Answer
apol.com.tw. 5 NS dns.octor.com.
apol.com.tw. 5 NS dns.apol.com.tw.
Authority
The response has no authority records.
Additional
dns.apol.com.tw. 5 A 61.20.46.204
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0