learn/phase-1/p1-w2/lesson 03
Week 2 · lesson 3

The Request Journey & Where Attacks Live

Hands-on. Ties each step to a class of attack.

What you'll learn

  • Trace a page load through its six steps: browser, DNS, TCP, TLS, HTTP request, response.
  • Name at least one attack that lives at each step.
  • Explain why each step is a different defensive responsibility.

The Request Journey & Where Attacks Live

When you type https://saarathiacademy.com and press Enter, four questions get answered: how does my computer find the site, connect to it, verify it is legitimate, and draw it on screen? Each answer is a step, and each step is where a different family of attacks lives.

Step 1, Browser

Before touching the network, the browser checks its cache, cookies, existing connections, and DNS cache.

Attacks here: malicious browser extensions, cookie theft, and XSS (malicious script running in your page).

Step 2, DNS (the phonebook)

Your computer only knows IP addresses, so it asks DNS to convert a name into a number:

google.com   →   142.250.x.x

Attacks here: DNS cache poisoning and malicious DNS servers that lie and send you to the wrong IP.

Step 3, TCP connection

With an IP in hand, the browser opens a TCP connection using the three-way handshake (SYN, SYN-ACK, ACK) before any real data flows.

Attacks here: SYN floods (exhaust the server with half-open connections) and port scanning (mapping which services are open).

Step 4, TLS

Once the TCP pipe exists, TLS turns it private: the two sides agree on keys and encrypt everything after. This is also where the site proves its identity with a certificate.

Attacks here: downgrade tricks, certificate problems, and users clicking past warnings.

Step 5, HTTP request

Inside the encrypted pipe the browser sends a request:

GET / HTTP/1.1
Host: example.com
User-Agent: Chrome

Attacks here: SQL injection, XSS, CSRF, and header manipulation, all the classic web-app bugs.

Step 6, Server response

The server replies with headers and a body (HTML, JSON, an image). The browser renders it, and the loop can repeat for the next resource.

Attacks here: leaked data in responses, insecure headers, and content that smuggles in step-5 attacks.

The big idea

Browser → DNS → TCP → TLS → HTTP request → response
   1       2     3      4        5            6

Almost every attack you will ever study attaches to one of these six slots. When something looks wrong, your first move is to ask: which step is this?

Try it

Run dig example.com in the terminal, that is Step 2 in isolation. Then ping example.com touches the lower network layers. You are walking the journey by hand.

Check your understanding

3 questions

Type an answer and press Check. Grading is keyword-based and forgiving, so short answers are fine.

  1. 1

    List the six steps of the request journey in order.

  2. 2

    Which step does SQL injection live at, and which step does DNS poisoning live at?

  3. 3

    Port scanning attacks which step of the journey?