DNS Leak Protection (2025/2026): How to Test & Fix DNS Leaks
Quick answer
A DNS leak happens when your device sends DNS requests to your ISP (or another resolver) outside the VPN tunnel. You may still see a “VPN connected” icon, but your browsing destinations can be inferred from your DNS queries. The fastest check: run our Leak Test and verify that your IP and DNS resolvers match your VPN.
SmartAdvisor Leak Scanner (Beta)
Don’t leave the site. Our tool compares your baseline network vs your current VPN session and highlights DNS, IPv6 and WebRTC risks in seconds.
Run DNS Leak Test Now → Open DNSCheck tool
Tip: save a baseline once, then re-run after changing VPN protocol (WireGuard / OpenVPN) or enabling “DNS leak protection”.
DNS leaks: the silent privacy killer
When you type a website name, your device asks a DNS resolver for the IP address. With a VPN, the goal is simple: web traffic and DNS should travel together inside the tunnel. If DNS goes outside, your ISP can still see the domains you look up, even if the page content is encrypted.
In 2026, DNS leaks are more than “a minor bug”. Your DNS pattern can act as a behavioural fingerprint: a unique mix of apps, update endpoints, streaming services and work tools. This is why DNS leaks can undermine even a strong VPN setup and why we treat them as a core privacy issue — not a cosmetic checkbox.
If DNS isn’t forced through the tunnel, you’re “wearing a mask” while your name tag is still visible.
Why DNS leaks are dangerous in 2026
- ISP and Wi‑Fi operator visibility: the resolver can log domains you request, even if the page content is encrypted.
- DNS hijacking / poisoning: in some networks, DNS replies may be altered to redirect you to phishing pages or ad-injected versions.
- Cross-session fingerprinting: a stable DNS pattern can help correlate “new IP” sessions back to the same user/device.
- Workplace risk: on corporate laptops, DNS leaks can expose internal tool usage and SaaS endpoints to untrusted networks.
Common causes of DNS leaks
| Cause | What it looks like | Quick fix |
|---|---|---|
| VPN app doesn’t enforce DNS | DNS resolver shows your ISP or public DNS unrelated to VPN | Enable “DNS leak protection”, switch protocol, or change provider |
| IPv6 mismatch | IPv6 DNS or IPv6 traffic bypasses tunnel | Enable IPv6 protection or disable IPv6 at OS/router level |
| DoH/DoT set in the browser | Browser uses its own resolver (not VPN’s) | Set browser DNS to “use system”, or use VPN’s DoH endpoint |
| Split tunnelling / per-app rules | Some apps leak DNS, others don’t | Exclude only safe apps; keep browsers and system DNS inside tunnel |
| Router / captive portal quirks | Leak appears only on specific Wi‑Fi/hotel network | Reconnect, flush DNS cache, and retest; consider a travel router VPN |
Video: why DNS leaks happen (and why they’re easy to miss)
Note: while this video is from a provider, it honestly covers the architectural limits of VPN technology — including why DNS can escape if your system routes resolvers outside the tunnel.
How to test for DNS leaks
If you want a fast, realistic check (without reading raw JSON), use our Leak Test. It shows DNS resolvers, IP, IPv6 and WebRTC indicators side by side. You can also run the standalone resolver check on https://dnscheck.smartadvisoronline.com/.
Try the SmartAdvisor Leak Scanner
We built our own diagnostic tool to help you identify DNS and IP leaks in seconds. No complex steps — just run the baseline and see the results.
Run My Privacy Test →How to fix DNS leaks on each platform
Start with the basics: switch to a modern protocol (WireGuard often performs better than OpenVPN), enable DNS leak protection, and verify you’re not overriding DNS in the browser. If you’re new to the fundamentals, see VPN Security Basics.
| Device | Steps that work | Extra checks |
|---|---|---|
| Windows | Enable leak protection; disable “Smart Multi‑Homed Name Resolution” only if needed; flush DNS cache | See VPN on Windows and retest |
| macOS | Use VPN app DNS mode; remove conflicting DNS profiles; reconnect to refresh resolvers | Check for iCloud Private Relay / third-party DNS apps |
| Android | Disable “Private DNS” if it bypasses the tunnel; ensure Always‑on VPN is enabled | Retest after changing networks (Wi‑Fi vs 5G) |
| iOS / iPadOS | Remove DNS/MDM profiles; toggle VPN; verify no “encrypted DNS” profile overrides system | Captive portals often cause temporary leaks — retest |
| Router / travel router | Use VPN DNS settings; avoid ISP DNS on WAN; ensure IPv6 rules match the tunnel | Consider a dedicated travel router for public Wi‑Fi |
A quick, repeatable workflow: baseline → VPN → fix → retest. It prevents “false confidence”.
The CAPTCHA hell (yes, it’s related)
DNS leaks don’t directly cause CAPTCHAs — but messy VPN configurations often correlate with unstable IP reputation, frequent server changes, and mixed routing. If you keep hitting “find the hydrant” checks on Google or Cloudflare, try a provider with cleaner server rotations or a dedicated IP. For broader fixes, keep this page bookmarked: VPN Troubleshooting.
Denys Shchur’s verdict
DNS leak is like wearing a mask but having your name tag pinned to your back. You think you are anonymous, but every step you take is being logged by your ISP. Don’t trust your OS to handle privacy — force it through the tunnel.
FAQ
What does a DNS leak look like in a test?
You’ll see DNS resolvers owned by your ISP (or unrelated public DNS) instead of your VPN provider. Retest after reconnecting.
Can a VPN still be “working” if DNS is leaking?
Yes. Your traffic can be encrypted while DNS requests escape. That’s why leak testing is essential.
Does Private DNS (Android) or DoH (browser) cause leaks?
It can. If your browser or OS forces its own resolver outside the tunnel, you may bypass the VPN’s DNS protection.
Does a DNS leak drain battery?
Indirectly: constant reconnects, extra retries, and heavy background encryption can increase battery use. A stable VPN protocol and correct DNS settings reduce overhead.
What if I want a browser that blocks DNS leaks at the core?
We’re working on SmartAdvisor Stealth Browser. If you want a privacy-first browser with leak-resistant defaults, keep an eye on our Knowledge Base hub.
