Online Tool Store
DNS Leak Explainer
Understand what a DNS leak is, why it happens with a VPN, and how to actually test for and fix one, with a clear step-by-step guide.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
1. What a DNS leak is
When you use a VPN, all your internet traffic — including DNS lookups (the requests that turn "example.com" into an IP address) — is supposed to route through the VPN's own DNS servers. A "DNS leak" happens when those lookups instead go through your regular internet provider's DNS servers, bypassing the VPN. Your provider (and anyone monitoring that traffic) can then see which sites you're visiting, even though your actual browsing traffic is still encrypted through the VPN.
2. Why leaks happen
Common causes include: the operating system falling back to its default DNS servers when the VPN's aren't reachable, "smart" DNS features in some routers or browsers that bypass the system's configured DNS, and IPv6 traffic leaking outside the VPN tunnel if the VPN only handles IPv4.
3. How to actually test for one
- Note your ISP's name (you can find this by searching "what is my ISP" without a VPN active).
- Connect to your VPN.
- Visit a dedicated DNS leak test website (search "DNS leak test") — these run a server-side check that a static page cannot.
- Compare the DNS servers shown against your VPN provider's known DNS servers. If your ISP's name or servers show up instead, you have a leak.
4. How to fix a leak
- Enable your VPN app's built-in DNS leak protection setting, if it has one.
- Manually set your VPN's DNS servers in your operating system's network settings.
- Disable IPv6 on your device, or confirm your VPN fully tunnels IPv6 traffic.
- Turn off "Secure DNS" / DNS-over-HTTPS settings in your browser that might route around your VPN's DNS.
How to use this explainer
- Read through the four sections above to understand what a DNS leak is and why it happens.
- Follow the step-by-step testing guide with a dedicated DNS leak test site while your VPN is active.
- If a leak shows up, work through the fix suggestions — starting with your VPN app's own leak protection setting.
FAQ
Why can't this page just run the test for me?
A real DNS leak test needs a server that receives your DNS lookup and logs which resolver actually reached it — that's fundamentally a server-side capability. This is a static, backend-free page (matching how every tool on this site works), so it can explain the concept and process but can't perform that server-side check itself.
Does having a VPN automatically prevent DNS leaks?
No — many VPN apps handle DNS routing correctly by default, but misconfigurations, certain operating system behaviors, and IPv6 traffic can all cause leaks even with a reputable VPN active. It's worth testing rather than assuming.
Is a DNS leak as bad as no VPN at all?
It's a meaningful privacy gap, though usually less severe than no VPN — your actual browsing traffic (the content) typically stays encrypted through the VPN tunnel even during a DNS leak; what leaks is the record of which domains you looked up, not the traffic itself.
Is anything about my connection sent anywhere by this page?
No. This page is a static explainer with no network checks of its own — nothing about your connection or DNS setup is sent to Online Tool Store or any other server.
How we compare
| Feature | Online Tool Store | dnsleaktest.com | Searching forums for an explanation |
|---|---|---|---|
| Runs an actual live DNS leak test | Not possible from a static page | ✓ | Not applicable |
| Clear, structured explanation | ✓ | Focused on the test, not the concept | Inconsistent quality |
| No ads | ✓ | Ad-supported | Varies |
For understanding what a DNS leak is and how to test for one honestly — without pretending a static page can run a server-side check — the Online Tool Store DNS Leak Explainer walks you through it clearly.