DNS Leak Test

Understanding DNS and Privacy

DNS (Domain Name System) translates website names like "google.com" into IP addresses that computers understand. Every time you visit a website, your device sends a DNS query. Normally, these queries go to your ISP's DNS servers, which means your ISP has a complete log of every website you visit — even if you use HTTPS.

How DNS Leaks Compromise Your VPN

When you connect to a VPN, all your traffic — including DNS queries — should be routed through the encrypted VPN tunnel. A DNS leak happens when some or all DNS queries bypass the tunnel and go directly to your ISP's DNS servers. This means your ISP (and anyone monitoring your connection) can see which websites you visit, even though your actual traffic data is encrypted.

Common Causes of DNS Leaks

• Windows Smart Multi-Homed Name Resolution — sends DNS queries to all available interfaces simultaneously
• IPv6 DNS queries — your VPN tunnels IPv4 but IPv6 DNS goes direct
• Misconfigured VPN — the VPN client doesn't override system DNS settings
• Transparent DNS proxies — your ISP intercepts and redirects DNS queries regardless of settings
• Browser DNS prefetching — browsers resolve domains before you click, sometimes outside the VPN

How to Fix DNS Leaks

1. Use a VPN with built-in DNS leak protection (like VPN XO)
2. Set custom DNS servers (1.1.1.1 or 9.9.9.9) on your network adapter
3. Disable "Smart Multi-Homed Name Resolution" on Windows
4. Disable IPv6 on your network adapter if your VPN doesn't support it
5. Use DNS-over-HTTPS (DoH) or DNS-over-TLS (DoT) for encrypted DNS

How This Test Works

This DNS leak test sends 6 sequential requests to VPN XO's servers from your browser, each forcing a fresh DNS resolution. We record the source IP address seen by our server for each request. If all requests show the same IP (your VPN's IP), your DNS is properly tunneled. If different IPs appear, some requests may be leaking outside your VPN tunnel.