When you’re comparing VPNs, there are a few tests you should run to ensure your connection is secure and private. One of the tests we recommend running is our DNS leak test.

Our DNS leak test only takes a few seconds and will let you know if your VPN is doing its job. In this guide, we’ll explain what a DNS leak is, why it matters, what causes it, and what you can do to fix it if your DNS requests are exposed.

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What is a DNS Leak

DNS stands for Domain Name System. It’s what translates human-readable URLs that appear in the address bar (e.g. www.security.org) into IP addresses that computers use to communicate online. Your internet service provider (ISP) normally handles DNS requests, which means they see which websites you’re visiting.

When you use a VPN, your DNS requests are supposed to be routed through the VPN’s private DNS server. However, when there’s a DNS leak, requests bypass the VPN’s DNS server and go to the ISP’s servers instead. That means even if the content of your traffic is encrypted, the ISP sees where they’re heading through the DNS requests.

The Dangers of a DNS Leak

Even if you’re ok with your ISP seeing your browsing activity, there are other consequences of exposing your DNS. These are some of the issues to be aware of:

• Data collection: Your ISP can log DNS queries and use them to build a profile on you, which they can then sell to advertisers and data brokers. They use the data to target ads and send spam. Some data brokers will also sell your personally identifiable information to the highest bidders.
• Government and ISP surveillance: In countries with aggressive data retention laws or censorship, DNS leaks expose browsing habits to government agencies. In some places, you won’t be able to access geo-restricted content if there’s a leak, even when connected to a VPN.
• Security risks: Unsecured networks like airport or cafe Wi-Fi can expose your activity to network administrators or hackers running spoofed servers. A DNS leak can also expose you to greater risks of threats such as man-in-the-middle attacks and data interception.

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What Causes VPNs to Leak DNS?

DNS leaks don’t happen randomly. There are several reasons why your DNS is exposed, such as:

• Operating system settings: Some operating systems prioritize system-level DNS settings over VPNs. For example, when IPv6 or smart networks are enabled in Windows – and if they are set to use your ISP’s DNS – they can override some VPN configurations.
• Split Tunneling: This feature lets some apps or services bypass the VPN connection. Depending on how you’ve enabled and configured split tunneling, it could cause your DNS queries to be exposed.
• Faulty VPN configuration: Some free VPNs or older apps may not properly enforce DNS routing, especially when switching networks or waking a sleeping device.

What to Do if Your DNS is Exposed

If your test results show a DNS leak, don’t panic. Most leaks can be fixed with a few changes. Here’s what we recommend:

• Enable DNS Leak Protection: Some VPNs include this setting. Make sure it’s turned on, especially on desktops and laptops.
• Update or Reinstall Your VPN: Outdated apps are more likely to cause DNS leaks. Make sure you’re running the latest version.
• Switch VPN Providers: Check out our VPN comparison guide to find a provider you can count on.

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Test Your VPN

Running a DNS leak test only takes seconds and gives you peace of mind that your VPN is doing what it promises. We recommend making it a regular part of your privacy routine, especially if you rely on a VPN for security and anonymity.