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Install a VPN and you might think your internet activities are fully protected from snoopers. With every site you access, all the data you transfer is sent through the VPN's secure encrypted tunnel and so keeping it safe from prying eyes. Unfortunately, if the VPN connection fails (e.g. server problem, weak Wi-Fi signal, overloaded network, etc) then your device may switch to your regular unprotected connection. Sites then get your real IP address, Wi-Fi hotspots might see the websites you're accessing, and the VPN won’t be encrypting any of your data. Most VPN providers handle this situation by offering a kill switch - although some give it a different name, like ExpressVPN's Network Lock or Windscribe's Firewall. But is this an effective solution? In this article we'll explain what a kill switch does, the different types of kill switches available, and how you can make sure your VPN kill switch is set up correctly. The idea behind a kill switch is simple. Essentially, if the VPN connection drops, the kill switch activates and blocks your device's internet access. This prevents you from accidentally sending data outside of the secure VPN tunnel, because if the tunnel fails then you won't be able to send any data at all. Every platform has its own tools for making this happen. An Android VPN app might use Android's built-in 'Always-on VPN' setting, for instance (Settings, Connections, More Connection Settings, VPN.) But Windows VPNs often use the Windows Filtering Platform (the technology behind Windows Firewall), and Mac and iPhone VPN apps have further techniques of their own. If the VPN drops, then however the kill switch kicks in, your VPN app usually tries to reconnect. Once the tunnel is up again, your internet access is automatically restored. As an aside, all this cross-platform complexity makes it challenging for VPN providers to offer a kill switch on every device type. Keep that in mind if you visit a provider's website and it boasts about having a great kill switch but doesn't list the supported platforms. Check the rest of the site, maybe in the Support pages, to find out if there's a kill switch on all apps. Although the concept of a kill switch is simple, the reality is more complicated, because every provider and app has its own way of working. There are two common approaches. The most popular type, such as ExpressVPN's Network Lock on Windows, only blocks your internet access if the VPN drops unexpectedly. If you manually disconnect or close the VPN app, the kill switch is disabled and you're free to browse as usual. But others (including NordVPN's Windows app) don't allow any internet access at all unless you're connected to the VPN. If you manually disconnect or close the app, you won't be able to get online until the VPN connection is re-established. This technology monitors your system, and if it detects a dropped connection, closes the apps you specify. You might tell the VPN app to shut down your browser and torrent client, for instance, ensuring they won't use an unprotected connection. Application-level kill switches don't offer much security. But they're also less likely to get in your way than the usual type, as they only affect the apps you specify and won't block anything else. If you only need the most basic protection for one or two apps, an application-level kill switch might be useful. But if you're looking for something more comprehensive, we'd stick with a system-wide kill switch. For more on this visit OUR FORUM.