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The Seven OSI Layers
The Seven OSI Layers The OSI model splits network communication into 7 layers . Memory trick (7 → 1): All People Seem To Need Data Processing . 7 Application, 6 Presentation, 5 Session, 4 Transport, 3 Network, 2 Data Link, 1 Physical. Layer 7: HTTP that the browser speaks. Layer 6: encoding and encr
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What this card says
What it is
The OSI model splits network communication into 7 layers.
Memory trick (7 → 1): All People Seem To Need Data Processing.
The 7 layers
7 Application, 6 Presentation, 5 Session, 4 Transport, 3 Network, 2 Data Link, 1 Physical.
Examples
Layer 7: HTTP that the browser speaks.
Layer 6: encoding and encryption, like TLS. HTTPS = HTTP + TLS.
ARP (maps IP to MAC address) sits between layers 2 and 3.
Why it matters for security
Each control works at a layer. Knowing the layer tells you what it can stop.
| # | Layer | Main function |
|---|---|---|
| 7 | Application | Interface for user applications; network services |
| 6 | Presentation | Translation, encryption, compression, data format |
| 5 | Session | Establish, maintain, terminate sessions; checkpoints |
| 4 | Transport | End-to-end delivery, ports, segmentation, flow & error… |
| 3 | Network | Logical addressing (IP), routing between networks |
Learn more in the lesson: 3.1 The Seven OSI Layers