There are a couple of ways to test for DNS leaks. While plenty of VPN services provide their own, one of the best ways is to use dnsleaktest.com. It’s straightforward, and it performs a series of tests which can help reveal leaks that don’t pop up every time.

When you first arrive on dnsleaktest.com, it’ll greet you and display both your IP address and location. You’ll also see two options; select Extended test. The website will try multiple requests to gain information about your connection. After each one, it’ll list the number of DNS servers it was able to trace.

When the test concludes, it should list all the servers it found with their IP addresses and owners. You should see only servers from your VPN host listed. If you see multiple different IPs, that’s usually an indication your DNS connection is leaking. If you did uncover a leak, you can always try a new configuration, then return to dnsleaktest.com for as many tests as it takes to fix.

What Can You Do?

There are two main steps you can take to prevent DNS leaks. The first, and most obvious, is to ensure your configuration is correct. This isn’t always in your hands, depending on how you connect but do what you can.

USING A VPN CLIENT

If you’re using a client from your VPN service, ensure you always have the latest version. Keep an eye on any options you have, and ensure they match your server and there aren’t any obvious mistakes. Some clients may even have explicit DNS options.

USING A CUSTOM CONFIGURATION

For those configuring their own client, you can comb through and make sure your settings match the server. Also, try to download new configuration files from your VPN provider regularly to prevent options from becoming outdated and incorrect. Mac and Linux users may also be able to script OpenVPN to change your system DNS to only use the VPN and revert back when you disconnect. Some Linux distributions provide these scripts.