Announcing experimental DDR in 1.1.1.1

What this post added

This post introduces and details the experimental deployment of Discovery of Designated Resolvers (DDR) in Cloudflare's 1.1.1.1 service. It explains the motivation for DDR, focusing on increasing the adoption of encrypted DNS transports. The post elaborates on the threat model, the mechanics of DDR (utilizing certificate-based authentication and SVCB records), and provides a concrete example of how to test it using `dig`. The implementation allows clients to discover and upgrade to secure DNS connections with the same resolver, ensuring authenticity.