What is a DNS leak?
Every time you open a website, your device first asks a DNS resolver to translate the domain name into an IP address. Those queries reveal every site you visit. When you connect to a VPN, the VPN should route DNS queries through its own encrypted tunnel to its own resolvers.
A DNS leak happens when your queries bypass the tunnel and go to your internet provider or another third-party resolver instead. Your traffic may be encrypted, but your ISP can still see — and log — the list of domains you look up.
How this DNS leak test works
We make your browser resolve several unique, random hostnames under a zone where we run the authoritative name server. Whichever resolver asks our server for those names is, by definition, the resolver your device is using.
We then look up each resolver's IP address in our geolocation database and show its operator and country. If you are on a VPN and you see your ISP's name, or a country different from your VPN server, your DNS is leaking.
How to fix a DNS leak
Enable the "DNS leak protection" or "use VPN DNS only" option in your VPN app. Disable IPv6 or make sure your VPN supports it, because IPv6 queries often leak around IPv4-only tunnels. On Windows, turn off Smart Multi-Homed Name Resolution; in browsers, disable "secure DNS" overrides that point to a provider outside the tunnel, or set it to your VPN's resolver.
よくある質問
Is it normal to see several DNS servers?
Yes. Large resolvers such as Google Public DNS or Cloudflare use many servers. What matters is who operates them, not how many there are.
I don't use a VPN. Do I need to worry?
Without a VPN your ISP's resolver is expected. You can still switch to a privacy-focused resolver with DNS-over-HTTPS to stop your ISP from logging lookups.
Does a DNS leak expose my IP address?
Not directly, but it reveals the websites you visit to your ISP and can reveal your real location even when your VPN hides your IP.