GLOSSARY · RECURSIVE RESOLVER
DNS resolver
A DNS resolver is the server that does the lookup work on your behalf. Your device asks it for a name, and it asks other DNS servers in turn until it finds the answer, then returns the result and keeps a copy for a while so repeat questions are quick.
Why it matters
Whoever runs your resolver sees every name you look up, together with your address. By default that is your internet provider or router, but you can choose a public resolver or let a VPN supply its own. This choice affects privacy, speed, filtering and the answers you get, which is why resolvers are the focus of a DNS leak test.
In practice
Your router often acts as a small forwarding resolver and passes questions to your provider's. In a DNS leak test, the resolvers shown are the servers that actually contacted the test's name server, which can differ from the ones listed in your settings. Large public resolvers may show several addresses, because they run many servers.
Related terms
- DNS: DNS is the internet's naming system.
- DNS leak: A DNS leak is when your device sends its DNS lookups to a resolver you did not intend, usually your internet provider's, while you believe a VPN or proxy is handling your traffic.
- ISP: An ISP is the company that connects you to the internet, whether through a cable, fibre, DSL, fixed wireless or mobile network.
- DoH: DNS over HTTPS wraps DNS questions and answers inside ordinary encrypted HTTPS traffic to a resolver, as described in RFC 8484.