What Is DNS — And Why Should VPN Users Care?
Every time you type a web address into your browser, your device sends a DNS query to translate that human-readable domain (e.g., example.com) into an IP address your computer can connect to. By default, these queries are handled by your Internet Service Provider's (ISP) DNS servers.
When you use a VPN, your browsing traffic is encrypted and routed through the VPN server. But here's the problem: in some configurations, DNS queries can bypass the VPN tunnel and travel directly to your ISP's servers — completely outside the encrypted connection. This is called a DNS leak.
Why DNS Leaks Are a Serious Privacy Risk
Even if your general browsing traffic is encrypted, a DNS leak means your ISP can still see every domain you visit. This defeats a significant part of the purpose of using a VPN. Your ISP can log this data, and in many jurisdictions is legally required to retain it. Government agencies, advertisers, or malicious actors who gain access to this data can build a detailed profile of your online activity.
How to Test for a DNS Leak
Testing is simple and free. Follow these steps:
- Connect to your VPN.
- Visit dnsleaktest.com or ipleak.net.
- Run the standard or extended test.
- Examine the results. The DNS servers listed should belong to your VPN provider — not your ISP.
If you see your ISP's DNS servers in the results while connected to a VPN, you have a DNS leak.
Common Causes of DNS Leaks
- VPN app misconfiguration: Some VPN apps don't properly route DNS through the tunnel by default.
- Windows Smart Multi-Homed Name Resolution: A Windows feature that sends DNS queries to multiple servers simultaneously for speed — which can bypass the VPN's DNS.
- IPv6 leaks: If a VPN only protects IPv4 traffic, IPv6 DNS queries can leak outside the tunnel.
- Manually configured DNS: If you've manually set a DNS server on your device (e.g., Google's 8.8.8.8), that setting may override the VPN's DNS.
How to Fix a DNS Leak
1. Enable DNS Leak Protection in Your VPN App
Most reputable VPN applications have a dedicated "DNS leak protection" or "private DNS" setting. Enable it. This forces all DNS queries to route through the VPN's own DNS servers.
2. Disable IPv6 If Your VPN Doesn't Support It
If your VPN provider doesn't fully handle IPv6 traffic, disable IPv6 on your network adapter. On Windows: go to Network Settings → Adapter Properties and uncheck IPv6. This is a temporary workaround until your VPN supports full IPv6 routing.
3. Use a VPN With Its Own DNS Servers
Choose a VPN provider that operates its own zero-log DNS servers and routes all queries through the encrypted tunnel by default. This is a feature worth verifying before subscribing.
4. Use Encrypted DNS as a Backup
DNS-over-HTTPS (DoH) or DNS-over-TLS (DoT) encrypts DNS queries independently of your VPN. Services like Cloudflare's 1.1.1.1 or Quad9 support these protocols. While not a substitute for proper VPN DNS routing, they add a layer of protection.
WebRTC Leaks: A Related Threat
While you're testing for DNS leaks, also check for WebRTC leaks. WebRTC is a browser technology that can expose your real IP address even while connected to a VPN. You can check for this at ipleak.net and disable WebRTC via browser extensions (like uBlock Origin) or in browser settings.
Final Checklist for Leak-Free Browsing
- ✅ DNS leak protection enabled in VPN app
- ✅ IPv6 disabled or handled by VPN
- ✅ WebRTC disabled in browser
- ✅ Kill switch active
- ✅ Verified clean results at dnsleaktest.com