DNS leak
When you visit a site, its name gets looked up by your local network's DNS, so others can tell where you are and what you visit. That is a DNS leak.
Think of it like this
You take a private car somewhere, but before leaving you ask the guard downstairs how to get there. The ride is private, yet the guard already knows your destination.
In this setup
A common cause is IP-based rules such as GEOIP,CN: to decide whether a site's IP is Chinese, the app first looks it up with a Chinese DNS. In this setup every IP rule carries no-resolve, so unlisted foreign sites are never looked up locally — leak tests only see overseas DNS on the server's side.
Common misconceptions
- "Any Chinese DNS in the test means a leak": using Chinese DNS for Chinese sites is normal; what matters is whether foreign sites are looked up with Chinese DNS.
- "A DNS leak exposes my exact IP": it usually exposes your province and provider.
Try it: Check for DNS leaks
Related: Domain names and DNS, Rule-based routing, WebRTC