DNS Resolution
DNS resolution is the process of translating a human-readable domain name (example.com) into an IP address that computers use to route connections. A full resolution involves: recursive resolver → root nameserver → TLD nameserver → authoritative nameserver. Cached results skip most steps.
Definition
DNS resolution follows a hierarchical delegation chain. First the OS checks its local cache. If not found, it queries the recursive resolver (usually the ISP or 8.8.8.8). The recursive resolver checks its cache. On a cache miss, it queries the root nameserver for the TLD (.com, .org), then the TLD nameserver for the registrar's nameserver, then the authoritative nameserver for the actual IP. The full chain can take 50–150ms on first lookup. TTL values control how long results are cached, trading freshness against performance.
Examples
- –dig example.com A – full resolution
- –dig +short example.com – just the IP
- –dig @8.8.8.8 example.com – use Google's resolver