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The OSI and TCP/IP models

The layers of a network exchange on a real frame: an HTTP request decoded byte by byte, the four nested envelopes, what each device reads and rewrites along the way, and which layer a failure belongs to.

  • 52 cards
  • 4 topics
  • Free
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The outline, topic by topic

Each topic is weighted the way the exam weighs it.

  1. The layers
  2. The frame for real
  3. Encapsulation
  4. Diagnosing by layer

A few cards from the deck

  • What is the OSI model?

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    A 7-layer reference model (physical, data link, network, transport, session, presentation, application) that splits network communication into responsibilities.

    It mostly serves as a shared vocabulary: people speak of a “layer 2 problem”. In practice the Internet follows the TCP/IP model.

  • A cable is unplugged. Which OSI layer is the problem at?

    • The transport layer (4)
    • The application layer (7)
    • The physical layer (1)
    • The network layer (3)
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    The physical layer (1)

    The medium itself (cable, radio signal) is layer 1: without it, no layer above can work.

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