A DNS (Domain Name System) leak test is a diagnostic tool used to determine whether a computer's DNS requests are being leaked to an unauthorized third party hacker. DNS is a system that translates human-readable domain names (such as www.iplocation.net) into IP address that computers can understand. DNS requests typically go through the user's ISP, but if the user's computer is configured to use a different DNS server, such as a public DNS server like Google DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1), the requests will bypass the ISP and go directly to the predefined DNS server.

A DNS leak can occur when a computer's DNS requests are not properly routed through the intended DNS server and instead go through the ISP or another unauthorized third party. This can happen due to misconfigured settings on the user's computer or router, or due to malicious software or hacking.

A DNS leak test typically involves accessing a website or using an application that can check whether DNS requests are being properly routed through the intended DNS server. The test may also check for other types of leaks, such as IPv6 leaks or WebRTC leaks. If a DNS leak is detected, the user may need to adjust their DNS settings or take other steps to secure their Internet connection and protect their privacy.