DNS egress check and DNS leak test
Before loading a site your browser resolves its name through DNS. This page resolves a few random subdomains and the authoritative server records which recursive resolver asked, revealing who actually handles your DNS and where that resolver sits.
If you use a proxy or VPN but the resolver is still your local ISP, you have a DNS leak: your local network can see which sites you visit, and split-routing rules may misfire. Enable remote DNS / Fake-IP in your proxy client or switch to encrypted DNS (DoH/DoT).
FAQ
What is a DNS leak?
When DNS queries bypass the VPN or proxy tunnel and go to your ISP's resolver directly.
Which public resolvers are common?
1.1.1.1 (Cloudflare), 8.8.8.8 (Google), 9.9.9.9 (Quad9); in mainland China 223.5.5.5 (Alibaba), 119.29.29.29 (Tencent), 114.114.114.114.
Related tools
More networking guides on the blog: 小磊哥の博客