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OSI Model

Completed Section

Before we can look at some practical networking stuff, we have to go over some boring jargon that you've probably heard of before. The OSI (Open Systems Interconnection) model is a theoretical model of networking. This model shows us how a packet traverses through a network in seven different layers. I won't get into specifics of this model, since most of these networking courses will be focused on the TCP/IP model, but it should be mentioned that such a theoretical networking model exists and has actually played a large part in the TCP/IP networking model that we use today.

OSI ✅

  • Abstraction or Concept of the Internet
  • Layer 1 to Layer 7
    • Layer 1 is physical
    • Layer 2 is data frames etc
    • Layer 3 is IP
    • Layer 4 is TCP/UDP. ports
    • Layer 5 - connection/session layer (linkerD?)
    • Layer 6 - Presentation
    • Layer 7 - App layer, HTTP, HTTPS etc
  • TCP/IP model
    • This model is another version that focusses on these layers Layer 3/4 & 7

Exercise

Read more about the OSI model: https://en.wikipedia.org/wiki/OSI_model

Quiz Questions

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Quiz Questions

1. What is used as the theoretical model of networking?

2. Which layer of the OSI model is responsible for routing packets across the network?

3. What layer in the OSI model ensures data is transferred reliably and error-free?

4. In which OSI layer would you find MAC addresses?

5. At which OSI layer does data encryption typically occur?

6. Which OSI layer handles the physical connection to the network medium?

7. Which layer translates between application formats and network formats?

8. What protocol operates at Layer 7 and is widely used for web browsing?

9. Which OSI layer is responsible for establishing, managing, and terminating sessions?

10. In which layer would you categorize a router's primary function?

Which layer of the OSI model handles encryption?