How to disable internet connection

1. Click on the Tools menu option in Internet Explorer, followed by the Internet Options-->option.
2. Choose the Connections tab from the Internet Options window.
3. Click on the LAN Settings-->button. The Local Area Network (LAN) Settings window will appear.
4. In the Proxy server section, check the box next to Use a proxy server for your LAN (These settings will not apply to dial-up or VPN connections).
5. In the Address: text box, enter 0.0.0.0.
6. In the Port: text box, enter 80.
7. Click OK and then click OK again in the Internet Options window.
8. Close all Internet Explorer windows.
9. If you wish to undo these changes in the future, simply follow the steps listed above again by just unchecking the box next to Use a proxy server for your LAN (These settings will not apply to dial-up or VPN connections) in step 4.

Keep in mind the following:

1. Since the Windows Update site requires the use of Internet Explorer, manual updates will no longer be possible. Automatic updates, if enabled, should continue unaffected.
2. Even though you may be disabling Internet Explorer, you are not actually removing it. Your Windows XP PC still uses Internet Explorer for a number of internal processes.
3. Updates related to Internet Explorer will still need to be performed because IE is still on your computer.

The another way of disconnecting internet is to modify your router to block the related ip address. You need to check your router's manual for details.