CAUSE
===================
When "UseDomainNameDevolution" is configured to 0, a single default entry is placed in the DNS suffix search list, for example "sub.domain.com.tw"

However, a devolutionized DNS suffix search list is populated if the entry is configured to 1, for example:
"sub.domain.com.tw"
"domain.com.tw"
"com.tw"

This is normal and a by-design behaviour

SUGGESTION
===================
Normally the client would uses domain name devolution to resolve an unqualified query. So it is normal be observe multiple DNS suffix entries under DNS suffix search list returned by ipconfig command.

We may manually disable it by:
1. Setting "UseDomainNameDevolution" (HKLM\Software\Policies\Microsoft\Windows NT\DNSClient) to 0
or
2. Manually populate the search list as described in Q275553 http://support.microsoft.com/KB/275553