crackthe.net
DNS and WebRTC leaks: when your real address slips out
What DNS leaks, WebRTC leaks, and IPv6 leaks are, why they can reveal you while the VPN is on, and what you can check and change yourself.
Key points
- A leak means some of your traffic or your real address reaches the outside world past the VPN tunnel.
- DNS leak: your device asks your internet provider, not the VPN, which address belongs to a website name. Your provider then sees which sites you visit.
- WebRTC and IPv6 leaks can reveal your real address to a website. Good VPN apps block all three; check the settings.
How a DNS leak happens
Before your browser opens a website, it asks a DNS server for the site’s address. With the VPN on, this question should go through the tunnel to the VPN’s DNS server. If it goes to your internet provider instead, the provider learns the names of the sites you open, even though the pages themselves travel through the VPN.
- Your deviceasks where a site is
- Your internet provideranswers, and learns the site name
- VPN servercarries the page itself
A DNS leak: the page goes through the tunnel, but the question about the site's address does not.
Three kinds of leaks
| Leak | What slips out | Who sees it | What helps |
|---|---|---|---|
| DNS leak | the names of the sites you open | your internet provider | the VPN app’s own DNS setting |
| WebRTC leak | your real IP address | the website, through the browser | the app’s WebRTC protection or browser settings |
| IPv6 leak | your real IPv6 address | the website | an app that routes or blocks IPv6 |
What you can check on this site
The IP check shows the address that reaches this website and its type, IPv4 or IPv6. If it shows an IPv6 address that is not your VPN’s while the VPN is on, your IPv6 traffic bypasses the tunnel.
The IP check does not test for DNS or WebRTC leaks. For those, you need a test that runs its own DNS server or reads your browser’s WebRTC data. Many VPN providers offer such a test on their website.
Settings that prevent leaks
- Use the app’s own DNS. Most VPN apps have a setting like “use VPN DNS” or “DNS leak protection”. Keep it on.
- Turn on the kill switch, so nothing leaves your device when the tunnel drops.
- Check IPv6. If your app does not support IPv6, turn on its option to block IPv6, or turn IPv6 off on the device.
- Use the VPN app, not only a browser extension. Many extensions only cover the browser and only act as a proxy.
Apps are not tested on this site. Whether a particular app blocks leaks cannot be checked from outside. Use the refund period to test it yourself.
Next step
Read Geoblocking, explained to see how websites decide which country you are in.
The figures in this guide come from the archive and change with every data update. As of October 17, 2026.
Check it with the archive's data
Read next: Geoblocking explained: why websites answer differently by countryAll guides