What Is a DNS Leak? How to Detect and Fix It on a VPN
A DNS leak happens when your device sends domain name lookups outside the encrypted VPN tunnel, straight to your internet provider. Even with a VPN connected, this quietly reveals which websites you visit. Understanding the leak helps you close it.
What a DNS lookup actually does
Every time you open a website, your device asks a DNS server to translate the human name, like example.com, into an IP address. These lookups act like a diary of everywhere you go online. Whoever answers your DNS queries can see the full list of domains you request, in real time.
Why a leak exposes you on a VPN
A VPN is meant to send both your traffic and your DNS lookups through its encrypted tunnel. A DNS leak means the lookups escape that tunnel and reach your ISP's default resolver instead. Your traffic may look private, but your provider still logs every domain you visit, defeating much of the point.
Common causes of DNS leaks
Leaks usually come from the operating system ignoring the VPN's DNS settings and falling back to a hardcoded resolver. Misconfigured networks, IPv6 traffic slipping past an IPv4-only tunnel, and split-tunneling rules are frequent culprits. Sudden network changes, like switching from Wi-Fi to mobile data, can also reset DNS to the provider default.
How to prevent DNS leaks
Use a VPN that forces all DNS through its own encrypted resolvers and blocks fallbacks. Enable the kill switch so traffic stops if the tunnel drops. Disable IPv6 if the VPN does not support it, and avoid manually setting a public DNS that bypasses the tunnel. A well-built app handles most of this automatically.
How to test for a DNS leak
Connect your VPN, then visit a DNS leak test site such as dnsleaktest.com and run the extended test. The results list every resolver handling your lookups. If you see your own ISP or your real country instead of the VPN's servers, you have a leak. Retest after any network change to stay sure.
Veepen routes your DNS through the same encrypted V2Ray/Xray tunnel as your traffic, so lookups never spill to your ISP. Install Veepen on Android or Android TV, import a VLESS Reality config from @veepen_vpn, and connect with a single tap.