How we prevent conflicts in authoritative DNS configuration using formal verification

Cloudflare describes Topaz, a production system that uses a custom DSL and Rosette/Z3-based formal verification to ensure authoritative DNS IP selection policies are satisfiable, reachable, and non-conflicting before deployment. The post outlines program structure (match/response/config), hot-path execution, centralized build-time verification (including conflict and semantic diff checks), and operational tradeoffs such as verifier maintenance and performance.