Follow a web request safely
Connect DNS, transport, HTTP, and TLS in a browser request.
- Trace a URL through name resolution to an HTTP response.
HTTP is an application-level request/response protocol. A request names a method and target; a response carries a status code, headers, and possibly a body. With HTTPS, TLS protects the connection and authenticates the server using certificates. DNS can find an address for a name, while a certificate helps verify that the peer is authorized for that name.
1request = {"method": "GET", "path": "/lessons", "host": "learn.example"}
2response = {"status": 200, "body": "Welcome"}
3print(f"{request['method']} {request['path']} → {response['status']}")
4print(response["body"])GET /lessons → 200 Welcome
A simplified HTTPS trip is: resolve the host name, establish a transport connection, negotiate TLS and check the certificate, then exchange HTTP messages. Modern HTTP can use different transport mappings, so this is a conceptual view of a common HTTP/1.1 or HTTP/2 connection.
Key takeaways
Trace a URL through name resolution to an HTTP response.
The code examples simulate protocol behavior; they do not send network traffic.
Use the layer model to locate where an address, port, or message belongs.
Lesson quiz
4 questions · pass with 3 correct · up to 50 XP
Passing this quiz completes the lesson and keeps your streak going. Questions you miss come back in review sessions later.
Practice: model networking concepts
Use small Python programs to model packet, address, and protocol behavior. These exercises run locally in your browser and do not send network traffic.
Classify a web URL
Read a URL and print HTTPS scheme: TLS expected for an https:// URL, or HTTP scheme: TLS not requested otherwise. This is a simple scheme check, not a real TLS verifier.
- HTTPS scheme
- HTTP scheme
Python runs in a sandboxed browser worker with a 60 second time limit. Its runtime loads from the Pyodide CDN; your code stays in this browser.
Questions about this lesson
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