Apex domains cannot have CNAME records.
Question and response
Question
dig catch.net.tw. NS
Answer
catch.net.tw. 4 NS dns01.catch.net.tw.
catch.net.tw. 4 NS dns02.catch.net.tw.
Authority
The response has no authority records.
Additional
dns01.catch.net.tw. 4 A 124.29.141.1
dns02.catch.net.tw. 4 A 124.29.141.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0