Rullst AcademyRullst Academy/Lesson
Internet, web and networks I · Lesson 09 / 10

Observe without guessing

Now the map meets a tool: the browser Network panel.

Learning paths14 min

Let's discover together

  1. 1

    For optional real practice, download this lesson kit, extract into a new folder and read README.md. With Python 3.11 or later, run python server.py on Windows or python3 server.py on macOS/Ubuntu. Keep the terminal open.

  2. 2

    Open http://127.0.0.1:8765/hello. In developer tools, choose Network and reload. Select /hello, check GET, status 200 and Content-Type text/plain. Menu names vary; do not paste scripts into Console.

  3. 3

    Visit /missing and /busy on the same address to observe deliberate 404 and 503 responses. Then stop the server with Ctrl+C and reload: a new request can fail without HTTP status. Our server uses no-store and only fixed paths, without listing your files.

  4. 4

    Record only fictional lab data. Do not share cookies, Authorization, tokens or HAR files from a personal session. If you cannot run Python, use the next lesson’s simulated workshop and label observations as simulated.

Your investigation notebook

Read, predict and explain. Every lesson has Markdown notes to edit, download and optionally publish on GitHub. ZIPs contain starter material, not your browser edits.

Optional practice: HTTP on your computer

Extract the kit into a new folder. Use Python 3.11+; python on Windows, python3 on macOS/Ubuntu. Run server.py, open http://127.0.0.1:8765/hello and inspect Network. Ctrl+C stops it. This lab has no external DNS, TLS, accounts or publishing. README.md explains port conflicts and tests.

# Windows
python -m unittest -v
python server.py

# macOS / Ubuntu
python3 -m unittest -v
python3 server.py
My files and GitHub

Official links and next step

✦
YOUR MISSION

Record method, target, status and type with a clear limit on conclusions.

Now it's your turn

Discovery workshop

Observe before concluding

In the local lab, GET /missing returned 404 with Content-Type: text/plain.
Build your answers and check when you are ready.
A moment to understand

Does this test prove external HTTPS works?

I need a hint

Return to the evidence: what was observed and what is still unknown?

Loading your journey…

Take it with you

Compare /hello and /missing and record what changed and stayed the same. Mark real or simulated practice. If using another port, use the same number in the command and URL.

At your own pace

My files and GitHub

Every lesson can become your own record: code, notes or a practice plan. Saving a file to GitHub is optional and does not change your XP.

Student guide

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