Apex domains cannot have CNAME records.
Question and response
Question
dig nap.net.tw. NS
Answer
nap.net.tw. 4 NS ns2.wonder.net.tw.
nap.net.tw. 4 NS ns1.wonder.net.tw.
Authority
The response has no authority records.
Additional
ns1.wonder.net.tw. 4 A 210.209.1.1
ns2.wonder.net.tw. 4 A 210.209.1.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0