VPN DNS Leaks: How to Detect, Fix & Prevent Them

What Is a DNS Leak?

When you type a website address like "wikipedia.org" into your browser, your device does not know where that website lives. It sends a DNS (Domain Name System) query — essentially asking "what is the IP address for wikipedia.org?" — to a DNS server. Without a VPN, this query goes to your ISP's DNS server, and your ISP logs which websites you visit.

When your VPN is working correctly, DNS queries should travel through the encrypted VPN tunnel and be resolved by the VPN provider's DNS server, not your ISP's. A DNS leak occurs when your device bypasses the VPN tunnel for DNS requests and sends them to your ISP's default DNS server instead. The result: your ISP can see every domain you visit, even though the actual data traffic is encrypted by the VPN.

DNS leaks are dangerous because they reveal your entire browsing pattern — not just individual pages but which websites you visit, how often, and at what times. This metadata is highly valuable to advertisers and invasive to your privacy. A study by the University of Oxford found that DNS data alone can identify individual users with over 90 percent accuracy when correlated across domains.

4 Types of VPN Leaks: Detection and Fix

DNS Leak

A standard DNS leak means your operating system is sending DNS queries to a server outside the VPN tunnel. This typically happens when Windows, macOS, or Android uses multiple DNS servers and prioritizes the ISP's server over the VPN's. On Android, certain OEM customizations by Samsung, Xiaomi, and Huawei have been known to override VPN DNS settings.

How to test: Visit dnsleaktest.com. Run the extended test. If any of the listed DNS servers belong to your ISP (Comcast, AT&T, BT, Vodafone, etc.) rather than your VPN provider, you have a DNS leak.

IPv6 Leak

Many VPNs only encrypt IPv4 traffic but ignore IPv6 entirely. If your network supports IPv6 and the VPN does not route it, your device will send IPv6 traffic — including DNS queries — outside the VPN tunnel. This is one of the most common leaks because IPv6 is often enabled by default on modern routers and mobile networks.

How to test: Go to ipv6leak.com. If you see any IPv6 addresses listed, your VPN is leaking. You should only see the VPN server's IPv4 address.

WebRTC Leak

WebRTC (Web Real-Time Communication) is a browser feature that enables voice, video chat, and P2P sharing without plugins. WebRTC can reveal your real IP address even when connected to a VPN because it uses STUN/TURN servers that bypass the VPN routing table. This affects all major browsers: Chrome, Firefox, Edge, and Brave.

How to test: Visit browserleaks.com/webrtc. If your real local IP address (typically starting with 192.168.x.x or 10.x.x.x) appears, WebRTC is leaking your network identity.

VPN Drop Leak

Even if your VPN is properly routing all traffic, what happens when the VPN connection drops for a split second? Without a kill switch, your device immediately falls back to the unprotected ISP connection. Apps, background services, and browser tabs that are actively communicating will send data in the clear before you even notice the VPN dropped. This is especially dangerous on mobile when switching between WiFi and cellular networks.

How to test: There is no tool for this — the best test is prevention. Check your VPN settings and confirm the kill switch is enabled. On Android, go to your VPN app settings and look for "Always-on VPN" and "Block connections without VPN" — both must be enabled.

5 Proven Fixes for DNS Leaks

1. Enable the VPN kill switch — This is the single most important setting. A kill switch blocks all internet traffic if the VPN connection drops, preventing any data from leaking onto the unprotected network. Shield VPN includes a kill switch that blocks both IPv4 and IPv6 traffic.
2. Use the VPN's private DNS servers — In your VPN app, look for DNS settings and select "Use VPN DNS" or "Private DNS." Avoid options like "Smart DNS" or "Split DNS" unless you fully understand the routing implications. These features often route some DNS queries outside the tunnel intentionally.
3. Disable IPv6 on your device — If your VPN doesn't support IPv6 (many still don't), disable IPv6 entirely in your device's network settings. On Android: Settings > Network & Internet > Advanced > Private DNS can help, but for full IPv6 leak protection, the VPN app must handle it natively.
4. Disable WebRTC in your browser — In Chrome: install an extension like WebRTC Leak Prevent. In Firefox: type about:config in the address bar, search for media.peerconnection.enabled, and set it to false. In Brave: go to Settings > Privacy and Security > WebRTC and toggle it off.
5. Set the VPN as Always-on on Android — Android has a built-in feature: Settings > Network & Internet > VPN > tap the gear icon next to your VPN > enable "Always-on VPN" and "Block connections without VPN." This ensures no traffic ever leaves your device unencrypted.

How Shield VPN Prevents DNS Leaks

Shield VPN operates private DNS servers on every VPN node, meaning your DNS queries are resolved by the same server that handles your encrypted traffic — there is no separate DNS pathway that could leak. All DNS resolution happens inside the encrypted WireGuard tunnel, and the kill switch blocks 100 percent of traffic if the tunnel drops. Additionally, Shield VPN blocks IPv6 traffic at the tunnel level, ensuring no IPv6 leak is possible.

Beyond DNS, Shield VPN implements full leak protection across all vectors: DNS leak protection (all DNS queries routed through the encrypted tunnel and resolved by Shield VPN's private DNS servers), IPv6 leak protection (IPv6 traffic is blocked at the tunnel interface level), WebRTC leak protection (the kill switch prevents WebRTC from establishing connections outside the tunnel), and kill switch protection (if the VPN drops for any reason, all traffic stops immediately — no exceptions, no grace period).

For a deeper dive into VPN protocols and encryption, read our guide on how VPN encryption works with WireGuard and AES-256.