If you have a domain and set a new nameserver for your domain, your computer will not access the server behind your new nameserver. It’s happened because your computer cached the DNS so when you trying to access your server using the domain, it will always redirected to previous server. The DNS cache will be updated automatically after period of time, max time for this update is 2 x 24 hours.
To manually flush your DNS cache on Windows XP, you can use this command in command prompt. Open your command prompt by pressing Windows Button + R, then type cmd.
Use this command.