Cloudflare Prevents DNS Conflicts with Formal Verification

2025-01-07

Cloudflare uses Topaz, a system that formally verifies the correctness of its internal DNS addressing behavior. Topaz encodes DNS business objectives as declarative programs, each with a match function, a response function, and a configuration. Before deployment, a custom model checker verifies these programs for conflicts and bugs, ensuring reliable and consistent DNS configuration. This improves internet reliability by preventing inconsistencies in IP address resolution.