Networking · Visual Explainer
How DNS Resolution Works
The concept
Your device asks a recursive resolver to do the legwork. It walks the hierarchy — root servers point to the TLD, the TLD points to the authoritative nameserver, and the authoritative server holds the answer. Every layer caches the result with a TTL.
Key distinctions
| Term | What it means |
|---|---|
| Recursive resolver | Your ISP or a public resolver (8.8.8.8, 1.1.1.1) hunts for the answer on your behalf and caches it. |
| Root → TLD → authoritative | The root says 'ask .com'; the TLD says 'ask ns1.example.com'; the authoritative server returns the actual IP. |
| Caching & TTL | Every layer caches with a time-to-live — total resolution is typically under 100ms cold, under 1ms cached. |
| Propagation | Isn't the record updating slowly — it's old cached answers living out their TTL across thousands of resolvers. |
Why it matters in practice
The professional move before any DNS migration is dropping the TTL a day in advance, so caches drain fast at cutover. Resolution succeeding and the connection working are two different layers.