What Is a DNS Leak? A 2-Minute Check for Your VPN

A DNS leak happens when your VPN is on, but the requests your phone makes to look up website names still go to the Wi-Fi network or your internet provider instead of through the VPN. The pages you open are encrypted, yet the list of sites you visit can still be seen by the network you are on.

Checked on 3 November 2026.

What is DNS, in plain words?

DNS is the internet's address book. When you type a site name, your phone first asks a DNS server for that site's number address, then connects to it. Each lookup names the site you are about to visit. On café, hotel or airport Wi-Fi, whoever runs the DNS server you use can see those names.

Why does a DNS leak matter on public Wi-Fi?

A VPN is meant to send all of your traffic, DNS lookups included, through its encrypted tunnel. If DNS leaks, the network owner or your provider can still build a list of the sites you visit, even though they cannot read the pages. On public Wi-Fi that list is exactly what you wanted to keep private.

How do you check your VPN for a DNS leak in 2 minutes?

Turn the VPN off. Open a DNS leak test site in Safari and run the standard or extended test.

Note the result. You will usually see your internet provider or the Wi-Fi network's DNS servers.

Turn the VPN on and wait until it says connected.

Run the same test again.

Compare. With the VPN on, the DNS servers listed should belong to your VPN service or its servers, not your home provider or the Wi-Fi network. If your provider still shows up, you have a leak.

What should you do if you find a DNS leak?

First, disconnect and reconnect the VPN, then test again; a leak sometimes appears only while the connection is starting. If it stays, check the app for a setting that sends all traffic through the VPN, update the app, and try a different protocol in the app's settings. If the leak is still there, contact the VPN's support team with your test result.

Frequently asked questions

Does a DNS leak show my passwords?

No. A DNS leak shows the names of the sites you look up, not what you type on them. Pages that use https stay encrypted either way.

Can a DNS leak happen on iPhone?

Yes, it can happen on any device, usually for a short time while the VPN connects or switches networks. Testing takes 2 minutes, so it is worth doing after you install a VPN.

Is a DNS leak the same as an IP leak?

No. An IP leak shows your real internet address. A DNS leak shows which sites you look up. A good test site checks both.

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CasperVPN encrypts your internet connection with WireGuard, OpenVPN, IKEv2 and CasperCloak, our own protocol, on iPhone and iPad (Mac app coming). Learn more in How to check your VPN is working or Download CasperVPN →