Apex domains cannot have CNAME records.
Question and response
Question
dig dynamic.seed.net.tw. NS
Answer
dynamic.seed.net.tw. 5 NS dns6.seed.net.tw.
dynamic.seed.net.tw. 5 NS dns5.seed.net.tw.
Authority
The response has no authority records.
Additional
dns5.seed.net.tw. 3 A 61.20.46.199
dns6.seed.net.tw. 3 A 61.20.46.200
dns5.seed.net.tw. 3 AAAA 2401:8000:0:0:0:0:0:101
dns6.seed.net.tw. 3 AAAA 2401:8000:0:0:0:0:0:102
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0