What happens when you open a URL?

Model answer (in order).

1. URL parsing and checking caches (browser, OS) for the page and for DNS.
2. DNS resolution: the resolver finds the IP address (recursive lookup: root → .com → example.com name servers), results are cached with a TTL.
3. TCP connection to port 443 (three-way handshake), then a TLS handshake: the server proves its identity with a certificate, and both sides agree keys for encryption.
4. HTTP request (GET /page, headers, cookies) over the encrypted connection; possibly HTTP/2 or HTTP/3.
5. The server (often behind a load balancer/CDN) processes it and returns a response: status code, headers, HTML.
6. The browser parses HTML, builds the DOM, fetches CSS/JS/images (more requests), builds the CSSOM, runs JavaScript, then does layout and paint.

Good answers mention caching at each layer and that HTTPS protects content but the DNS lookup and server name can still be visible.