What happens when you type a URL and press Enter?

Question

IT Interview Practice · Accepted Answer

Typing a URL kicks off a chain of network steps: the browser figures out the server's IP address, opens a connection to it, sends an HTTP request, receives the response, and renders the page. Here is the end-to-end flow for `https://example.com`:

```text
You type https://example.com
   │
   ▼
1. URL PARSE   split scheme (https) + host (example.com) + path (/)
   │
   ▼
2. DNS         example.com ──▶ 93.184.216.34   (resolve name → IP)
   │
   ▼
3. TCP         3-way handshake to 93.184.216.34:443  (open connection)
   │
   ▼
4. TLS         handshake: verify certificate + agree on keys (encrypt)
   │
   ▼
5. HTTP        GET / HTTP/1.1   Host: example.com   (send request)
   │
   ▼
6. RESPONSE    200 OK + HTML   (server replies)
   │
   ▼
7. RENDER      parse HTML → fetch CSS/JS/images → build DOM → paint
```

**DNS** turns the human-readable name into an IP address, usually served from a cache (browser, OS, or resolver) so it costs nothing on repeat visits. **TCP** then establishes a reliable connection with the server on port 443. Because the URL is `https`, a **TLS** handshake follows: the browser checks the server's certificate and both sides derive session keys so the traffic is encrypted. Only now does the browser send the actual **HTTP request** (`GET /`). The server returns a **response** — a status code plus HTML. The browser parses that HTML, discovers references to CSS, JavaScript, and images, fetches those (often in parallel), builds the **DOM**, and paints pixels to the screen.

## Why it matters

This is one of the most common interview questions precisely because it touches every layer of the stack — DNS, TCP, TLS, HTTP, and rendering — in one story. A strong answer shows you understand how the pieces connect rather than memorizing any single protocol. It also opens the door to deeper follow-ups: caching, connection reuse, latency, and where things can fail, which are exactly the topics that matter when you debug a slow or broken page in production.

Why it matters

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