DNS Studio
Studio tools

How DNS Works

Step-by-step technical explanation of the DNS resolution process

Understanding how DNS works helps you troubleshoot issues, optimise performance, and make informed decisions about DNS configuration. Let's walk through the complete DNS resolution process step by step.

The DNS Resolution Process

When you type a domain name in your browser, DNS performs a series of queries to find the corresponding IP address. Here's what happens:

  1. Browser Cache Check — Your browser first checks its local DNS cache for previously resolved domains. If found, it uses the cached IP address immediately.
    Result: Cache hit = instant resolution | Cache miss = continue
  2. Operating System Cache — If not in browser cache, the OS checks its DNS cache. Both Windows and Unix-like systems maintain DNS caches.
    Result: OS cache hit = return to browser | Cache miss = continue
  3. Router/Local Network Cache — Your router or local network DNS cache is checked. Many routers act as DNS forwarders.
    Result: Network cache hit = return | Cache miss = continue
  4. Recursive DNS Resolver Query — Your computer queries a recursive DNS resolver (usually provided by your ISP). This server performs the full lookup on your behalf.
    Common resolvers: 8.8.8.8 (Google), 1.1.1.1 (Cloudflare), ISP DNS
  5. Root Nameserver Query — The recursive resolver queries one of 13 root nameservers (a.root-servers.net through m.root-servers.net) to find the TLD nameserver.
    Root servers: Manage top-level domains (.com, .org, .net, etc.)
  6. TLD Nameserver Query — Root server responds with the TLD nameserver address. Recursive resolver queries the TLD nameserver (e.g., .com nameserver) for the domain's authoritative nameservers.
    TLD servers: Manage specific domain extensions
  7. Authoritative Nameserver Query — TLD server responds with authoritative nameservers for the domain. Recursive resolver queries the authoritative nameserver directly for the DNS record.
    Authoritative servers: Hold the actual DNS records
  8. IP Address Returned — Authoritative nameserver returns the IP address (for A record) or other DNS record data. Recursive resolver caches the result and returns it to your computer.
    Result: Domain resolved to IP address
  9. Website Loads — Your browser receives the IP address, establishes a TCP connection, and loads the website.
    Final step: HTTP/HTTPS connection to web server

DNS Hierarchy

DNS Caching

DNS caching significantly improves performance by storing DNS responses at multiple levels:

Cache Levels

TTL (Time To Live)

Every DNS record has a TTL value (in seconds) that determines how long it can be cached: 

Low TTL (300s): Faster updates, more queries
Medium TTL (3600s): Balanced (default)
High TTL (86400s): Slower updates, fewer queries

DNS Query Types

Recursive Query

Client asks DNS server to find the answer, and the server performs all necessary queries to return a complete answer.

Client → Resolver → Full lookup → Answer

Iterative Query

DNS server responds with the best answer it has, or refers to another nameserver. Client performs multiple queries.

Client → Multiple queries → Final answer

Non-Recursive Query

Server already has the answer in its cache, so it returns immediately without querying other servers.

Client → Cached answer → Immediate response

Factors Affecting DNS Performance

⚡ Speed Factors

🐌 Slowdown Factors

See DNS Resolution in Action

Use our free DNS checker to see how DNS resolution works across 39+ global locations

Check DNS Resolution →

Related guides