Flush DNS cache in Windows 7 and Vista (works on all WinOS)
Step 1. Hit Windows key and type in cmd (do not hit enter).
Step 2. In the search results that come up, right click “cmd” and run as administrator. When the screen flashes and asks for permission, accept it.
Step 3. In the command prompt, type in ipconfig /flushdns (or right click and paste it to the command prompt) and hit return.
Step 4. You should see the confirmation as shown below:
Flush DNS cache in Windows XP
Hit Windows+R to bring up the Run dialog box.
Type cmd and hit ok.
In the command prompt that comes up, enter ipconfig /flushdns and hit return.