Astrill Setup Manual:How to flush DNS cache on Windows Vista
STEP 1 - Run Command Prompt as Admin
1. Click on Windows Startup menu.
2. Type cmd (do not hit enter).
3. In the search results that come up, right click on cmd.
4. Choose Run as administrator. When the screen flashes and asks for permission, accept it.
STEP 2 - Flush DNS cache
1. In the command prompt, type in ipconfig /flushdns then press Enter key.
2. This is a confirmation that you have Successfully flushed the DNS resolver cache.