The Windows "Primary DNS suffix" is by default used for resolving unqualified domain names (names with no dots).
In the Windows Control Panel, double-click the "System" icon:
In the "System Properties" dialog, select the "Computer Name" tab and click the "Change..." button:
In the "Computer Name Changes" dialog, click the "More..." button:
Enter the primary DNS suffix:
For more information, please see the following knowledge base articles: