Proxy detection test

They compare what the connection says with what the browser says: the kind of network behind the address, the time zone against where the address sits, the address WebRTC reveals, the TCP handshake against the operating system the browser names, and headers a proxy adds on the way. On top of that most bot checks keep a record of what each address has done before.

People browse from home and mobile lines, while addresses of hosting companies belong to servers. Most sites therefore treat a datacenter address as a proxy, a VPN or a bot before they look at anything else.

WebRTC opens its own connection for calls and file transfers. When that connection goes around the proxy, the site sees a second public address, usually the real one, and the WebRTC check lists every candidate it found.

Not from the address alone: free datasets cannot tell a residential proxy from an ordinary home line, which is why this page never claims one. What still gives one away is inconsistency, such as a clock set to another country or a server's TCP stack under a Windows browser, and the history the address already has at the site.

An ordinary website cannot see which resolver you use, so it is not a detection signal. Whether your lookups go around the tunnel is a privacy question, answered by the DNS leak test.