Great breakdown of how DNS resolution works. One thing worth adding once you understand this flow is the ability to query DNS records programmatically. WhoisFreaks has a DNS Lookup API that lets you fetch A, MX, NS, TXT and other record types for any domain. Useful when you are building tools that need to verify domain configuration, debug DNS propagation issues, or monitor DNS changes over time. Fits naturally into the system design and troubleshooting use cases you mentioned at the end.