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Why Windows Leaks DNS More Than Other Operating Systems
Windows is the most common platform for DNS leaks, and there are several reasons for this. Microsoft's Smart Multi-Homed Name Resolution feature, enabled by default on Windows 10 and some Windows 11 builds, sends DNS queries across all available network interfaces simultaneously. If you're connected to a VPN and also have a WiFi or Ethernet connection active, your DNS queries can escape through the non-VPN interface — completely bypassing your encrypted tunnel.
Windows also caches DNS results aggressively, which means that even after connecting to a VPN, previously resolved domains may still reference your ISP's DNS servers. Additionally, Windows Update and background services can trigger DNS lookups outside the VPN tunnel.
How Windows DNS Resolution Works
When you type a URL into your browser on Windows, the operating system checks its local DNS cache first. If the domain isn't cached, Windows sends a query to whichever DNS servers are configured on your active network adapter. If multiple adapters are active (for example, WiFi and a VPN adapter), Windows may send queries over both unless explicitly configured not to. This is the core mechanism behind most Windows DNS leaks.
Understanding this is critical because it means simply connecting to a VPN isn't always enough. You need to ensure Windows is configured to only use the VPN's DNS servers while the VPN is active. For more on how DNS leaks work, see what is a DNS leak.
Step-by-Step Fix for Windows 10 and Windows 11
- Open Settings → Network & Internet → Advanced network settings → Change adapter options.
- Right-click your primary network adapter and select Properties.
- Select Internet Protocol Version 4 (TCP/IPv4), click Properties, and set DNS to a secure provider like 1.1.1.1 or 9.9.9.9.
- Disable IPv6 on the adapter if your VPN doesn't support it — this prevents IPv6 DNS leaks.
- On Windows 10, disable Smart Multi-Homed Name Resolution through the Group Policy Editor. See our dedicated guide for instructions.
- Flush your DNS cache: open Command Prompt as Administrator and run
ipconfig /flushdns. - Connect to your VPN and run our free DNS leak test to confirm the fix.
If your VPN provider offers a DNS leak protection toggle, make sure it's enabled. For broader fixes across all platforms, see our complete DNS leak fix guide.
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