How we prevent conflicts in authoritative DNS configuration using formal verification

This post details the technical implementation of formal verification within Cloudflare's Topaz system for authoritative DNS configuration. It explains the structure of Topaz programs (config, match, response functions), the domain-specific language (topaz-lang) based on Scheme, and how these programs are executed sequentially to determine IP addresses for proxied domains. The post provides concrete examples of Topaz programs, including one for a specific tag ('orange') and a more complex one involving datacenter selection, traffic percentage, and IP prefix distribution. It highlights the use of functions like `fetch_datacenters`, `rand_gen`, `hash`, `member?`, `random_number`, `range`, `select_from`, and `ttl` within the DSL. The core contribution is the application of formal methods to ensure correctness and prevent conflicts in a critical network system.