Check My DNS is a custom developed DNS nameserver that creates dynamic delegated subdomains to enable clients to query for never-seen-before resource records in order to support a general-purpose framework for testing DNS resolvers.

Read more about it here.

Version 3 is has been rolled out and is actively being developed. There are no longer instances, you instead can select a region to test against. Much more to come!

There is also a command line client (cmdns-cli) that you can run locally, this will allow you to specify which resolver to test against.

As a DNS-OARC member you can get access to all of the raw test data on our analysis servers, if you wish to have access but currently don't have access to the analysis servers please contact us.