Microsoft windows operating system stores DNS look-ups in a cache to speed connection to previously visited websites.
Sometimes bad results will be cached and therefore needs to be cleared in order to communicate with the host correctly.
You can flush DNS by following the simple steps:
- Open “Command Prompt”
- Press Windows Key+R (will open run)
- Type cmd
- And press Enter
     2.Type ipconfig/flushdns  and press enter
All the entries in the DNS cache will be deleted,to find out how to see the entries in the DNS cache see here
