Trusted Recursive Resolver
DNS-over-HTTPS (DoH) allows DNS to be resolved with enhanced privacy, secure transfers and comparable performance. This page describes Firefox configuration settings related to DoH in detail, and offers some explanation of internal operations of the implementation.
Mozilla operates a Trusted Recursive Resolver program, whose requirements are documented at Security/DOH-resolver-policy. All TRRs offered by Firefox conform to the requirements described in the policy, but not vice versa().
For more information, we've created documentation about DoH and our plans for deployment. We also have an FAQ, and instructions for network operators who wish to disable DoH on their networks.