The Domain Name System (DNS) is responsible for converting domain names, e.g.,, into Internet Protocol addresses that are used to route traffic on the Internet. To convert a domain name, your computer issues a DNS resolution request which is performed on your behalf by a set of servers known as DNS resolvers.

This tool is designed to help you learn about how your DNS resolutions are being handled. It works by sending specifically designed DNS resolution requests that cause the DNS infrastructure to interact with a server under our control. In addition to discovering the DNS resolvers that you are using, we also test the resolvers for vulnerabilities to several well known attacks.