Apex domains cannot have CNAME records.
Question and response
Question
dig cl.static.apol.com.tw. NS
Answer
cl.static.apol.com.tw. 5 NS dns.octor.com.
cl.static.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
dns.octor.com. 5 A 61.20.46.203
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0