DNS Resolution Explained: Recursion, Iteration, Cache and TTL
A Full Resolution
Typing example.com triggers a DNS query that eventually returns the domain's IP. Multiple DNS server tiers cooperate to produce the answer.
Recursive vs Iterative
Your configured resolver (e.g. 8.8.8.8 or 223.5.5.5) recurses on your behalf, walking root, TLD, and authoritative servers step by step before returning the final answer.
Cache and TTL
Every answer carries a TTL (Time To Live) in seconds. Short TTLs propagate changes faster but increase query load; long TTLs do the opposite.
Troubleshooting Tips
- nslookup domain: check what your system resolver returns.
- nslookup -type=NS domain: verify authoritative servers.
- dig domain @8.8.8.8: bypass local cache and query a public resolver.
- If resolution works but pages do not load, check hosts, proxy and browser cache.