Feature
DNS and IPv6 Leak Protection and Kill Switch in V2Duo
Make sure nothing slips past the tunnel: no DNS requests, no IPv6 traffic, and nothing at all while the app is closed.
A safe connection takes more than a good config. Sometimes part of your traffic leaves around the tunnel without you knowing: DNS requests, IPv6 traffic, or everything during the moment the tunnel is down. This guide covers what V2Duo does about each, and what you should do.
What is a DNS leak?
Even if your main traffic goes through a config, DNS requests that go straight to your provider's DNS show them which sites you open. In some countries the answers for blocked sites are also tampered with.
V2Duo gives the system a private DNS address inside the tunnel and answers every request itself. By default those answers come from encrypted DNS, through your configs. Apps that set their own DNS to 8.8.8.8 or 1.1.1.1 go through the same path. Choosing a DNS server is covered in the DNS mode guide.
Leak protection on Windows
On Windows, "DNS & IPv6 leak protection" is on by default. While connected:
- Windows lets no DNS request leave through any other adapter;
- IPv6 traffic is blocked. V2Duo does not carry IPv6 through the tunnel yet, and blocking it beats leaking it.
These rules are active only while you are connected and are removed when you disconnect.
What is a kill switch?
A kill switch cuts your internet if the tunnel goes down for any reason, such as the app closing or the phone restarting, so no app connects directly.
The kill switch on Android
Android has a kill switch built into the system, and that is the most reliable option, because Android enforces it even if V2Duo is closed:
- In V2Duo, open Settings and tap the kill switch button to open Android's VPN settings.
- Tap the gear icon next to V2Duo.
- Turn on "Always-on VPN".
- Turn on "Block connections without VPN" too.
From then on, if V2Duo is not connected, no app can reach the internet.
The kill switch on Windows
The current Windows version has no separate kill switch, and if the connection ends, Windows goes back to normal. The V2Duo service runs steadily while you are connected, and if one of your links drops, traffic continues over the others. A Windows kill switch is on our list.
A simple check
After connecting, open a DNS leak test site in your browser. The DNS servers it lists should belong to the DNS you chose or to your config's server, not to your internet provider.
Frequently asked questions
Does blocking IPv6 cause problems?
Almost every site is reachable over IPv4 too. IPv6 comes back as soon as you disconnect.
Does Android's kill switch use battery?
No. It is a system feature that only decides whether traffic may leave without the VPN.
What happens when the phone restarts?
With Always-on VPN, Android starts V2Duo's connection by itself after booting.
Ready to try it?
V2Duo is free and takes a minute to install.
The V2Duo team wrote this guide from tests on real devices and updates it with every release. How we test