Previously, if you wanted to build your own authoritative DNS system for a website, the (almost) only option was PowerDNS with its GeoIP backend. However, the GeoIP backend uses YAML configuration files and cannot work with databases like MySQL. This meant having to manually set up a cross-server file synchronization system instead of using more mature database synchronization technologies. Fortunately, PowerDNS added support for Lua records in its latest 4.2 version. Lua is a programming language specifically designed for "embedding functionality into other programs," which you may have encountered in nginx (as a plugin). Lua record support enables PowerDNS to return different responses based on user query requests, thus implementing GeoDNS functionality for regional resolution....