Apex domains cannot have CNAME records.
Question and response
Question
dig pni.tw. NS
Answer
pni.tw. 5 NS alan.ns.cloudflare.com.
pni.tw. 5 NS fiona.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0