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What Causes DNS Leaks?
A DNS leak happens when your DNS queries bypass your VPN tunnel and are sent directly to your Internet Service Provider's DNS servers. This exposes every website you visit to your ISP, even when you believe your traffic is encrypted. Common causes include misconfigured network adapters, operating system defaults that override VPN settings, and VPN software that fails to route DNS requests through its own servers.
On Windows, a feature called Smart Multi-Homed Name Resolution can send DNS queries to all available network interfaces simultaneously, including those outside your VPN tunnel. On Mac, network service ordering and custom DNS configurations can also result in DNS requests leaking outside a secure connection.
Not sure what a DNS leak actually is? Read our guide on what a DNS leak is before continuing.
How to Fix DNS Leaks on Windows 10 & 11
Windows is one of the most common platforms for DNS leaks. Follow these steps to lock down your DNS settings:
- Open Settings → Network & Internet → Change adapter options.
- Right-click your active network connection and select Properties.
- Select Internet Protocol Version 4 (TCP/IPv4) and click Properties.
- Choose "Use the following DNS server addresses" and enter a secure DNS provider such as 1.1.1.1 (Cloudflare) or 9.9.9.9 (Quad9).
- Repeat for Internet Protocol Version 6 (TCP/IPv6), or disable IPv6 entirely if your VPN does not support it.
- On Windows 10, disable Smart Multi-Homed Name Resolution via the Group Policy Editor to prevent DNS queries from being sent over all interfaces. See our Smart Multi-Homed Name Resolution fix guide for details.
- Flush your DNS cache by opening Command Prompt and running
ipconfig /flushdns.
For a more detailed Windows walkthrough, visit our Windows DNS leak test page.
How to Fix DNS Leaks on Mac
macOS generally handles DNS better than Windows, but leaks can still occur — especially on public WiFi networks or when using a VPN that doesn't enforce its own DNS servers. Here's how to fix it:
- Open System Settings → Network and select your active connection (WiFi or Ethernet).
- Click Details → DNS.
- Remove any existing DNS servers and add a secure provider such as 1.1.1.1 or 9.9.9.9.
- Click OK and then Apply.
- Flush your DNS cache by opening Terminal and running
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder.
For Mac-specific guidance, see our Mac DNS leak test page.
How to Verify Your Fix Is Working
After making changes, it's essential to confirm that your DNS queries are no longer leaking. The fastest way is to use our free DNS Leak Checker. Connect to your VPN, run the test, and check whether the DNS server shown belongs to your VPN provider — not your ISP.
If your ISP's DNS servers still appear in the results, double-check that your VPN is connected, your manual DNS settings are saved, and your DNS cache has been flushed. Some VPN providers also offer a built-in DNS leak protection toggle — make sure it's enabled.
Concerned your VPN might still be leaking? Check our guide on VPN DNS leaks to learn what to look for.
Not sure if your DNS is leaking? Find out in seconds.