DNS Leaks Explained: How to Test and Fix Them

A DNS leak happens when your device sends DNS requests — the lookups that turn website names into IP addresses — outside your encrypted VPN tunnel, exposing which sites you visit to your internet provider even though you appear “protected.” It quietly defeats much of the privacy a VPN is supposed to give you. The good news: DNS leaks are quick to test for and usually easy to fix. Here’s how.

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What is DNS, and what leaks?

Every time you visit a site, your device asks a DNS resolver to translate the domain (like coppers.io) into an IP address. Normally your VPN should route these lookups through its own encrypted tunnel and its own DNS servers. A DNS leak is when those requests instead go to your internet service provider’s DNS servers — revealing your browsing to your ISP and undermining your privacy, even while the VPN looks connected. For the wider context, see what to use a VPN for .

Why DNS leaks happen

• Manual or default DNS settings that override the VPN’s DNS.
• Operating-system quirks — Windows “smart multi-homed name resolution” can query several resolvers at once.
• IPv6 traffic the VPN doesn’t handle, slipping outside the tunnel.
• A dropped VPN connection with no kill switch to stop traffic.
• Transparent DNS proxying by some ISPs that intercept requests.

How to run a DNS leak test

Testing takes a minute:

1. Connect your VPN as you normally would.
2. Open a DNS leak test site (search “DNS leak test”) and run the standard or extended test.
3. Check the results — they list which DNS servers answered your lookups.
4. Interpret it: if the servers belong to your VPN provider (and the location matches your VPN, not your home), you’re fine. If you see your ISP’s name or your real location, that’s a leak.

Re-run the test after reconnecting or switching servers to be sure.

How to fix and prevent DNS leaks

Most leaks are fixable in a few steps:

• Use a VPN that runs its own DNS with built-in DNS-leak protection (most reputable ones do).
• Enable the VPN’s kill switch so traffic stops if the tunnel drops.
• Disable IPv6 if your VPN doesn’t support it — or choose one that does.
• On Windows, turn off smart multi-homed name resolution, or rely on the VPN app’s leak protection.
• Set a trusted DNS manually (your VPN’s, or a privacy resolver) if needed.
• Re-test to confirm the leak is gone.

If your VPN still leaks after all this, that’s a strong reason to switch — see how to choose a VPN .

DNS leaks vs IP and WebRTC leaks

A DNS leak is one of three common VPN leaks:

• DNS leak — exposes the sites you look up.
• IP leak — exposes your real IP address, often via IPv6.
• WebRTC leak — a browser feature that can reveal your IP even on a VPN.

A good VPN with leak protection and a kill switch guards against all three. Knowing your VPN protocol and settings helps too.

The bottom line

A DNS leak sends your browsing lookups outside the VPN tunnel to your ISP, silently undoing the privacy you switched the VPN on for. Test for it in a minute with any DNS leak test, and fix it by using a VPN with its own DNS and leak protection, enabling the kill switch, and handling IPv6. If leaks persist, switch to a more capable VPN — solid leak protection is non-negotiable for real privacy.

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