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The TCP/IP Model and OSI Comparison
The TCP/IP Model and OSI Comparison The TCP/IP model is the real internet model, with 4 layers. The OSI model has 7 layers and is mostly for teaching. Application = OSI 5–7. Transport = 4. Internet = 3. Network Access = 1–2. AWS security groups filter IP and port (layers 3–4). They cannot see SQL in
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What this card says
What it is
The TCP/IP model is the real internet model, with 4 layers.
The OSI model has 7 layers and is mostly for teaching.
How they map
Application = OSI 5–7. Transport = 4. Internet = 3. Network Access = 1–2.
Why it matters for security
AWS security groups filter IP and port (layers 3–4). They cannot see SQL injection inside HTTPS.
AWS WAF works at layer 7 and can. So use both.
Common mistake
Arguing “4 layers or 5 layers”. Both are fine if you explain the mapping.
| Point | OSI model | TCP/IP model |
|---|---|---|
| Layers | 7 | 4 (or 5) |
| Developed by | ISO (reference/theoretical) | US DoD / DARPA (practical) |
| Approach | Model first, protocols later | Protocols first, model later |
| Session & presentation | Separate layers | Merged into Application |
| Usage | Teaching, troubleshooting vocabulary | Actual internet implementation |
Learn more in the lesson: 3.3 The TCP/IP Model and OSI Comparison