How we prevent conflicts in authoritative DNS configuration using formal verification

Cloudflare details Topaz, a production system that selects IP addresses for authoritative DNS responses via a simple DSL and formally verifies policy behavior using a Rosette/Z3-based model checker for satisfiability, reachability, and conflicts before deployment. The post explains policy structure (match, response, configuration), distribution via QuickSilver, verification-driven feedback like conflict detection and semantic diffs, and the practical trade-offs of bringing formal methods to networked systems.