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Domain 4: Network Security

Study Notes

OSI Model

  • Globally agreed upon set of standards and protocols that are used for different devices to communicate with each other

    • Created ​so different companies like Microsoft, Oracle, IBM, HP or Sony can all make devices that can agree on a set of rules in order to make their proprietary devices communicate with each other.  

      • Otherwise one single company would have to make every single electronic product out there.  It just wasn't going to work that way - the world needed the OSI Model! ​

  • Separates the different types of communication mechanisms within a single system into different layers

    • Operating systems mostly handle application layer stuff​

    • Networking devices handle routers or firewalls

    • Single broadcast domain networks can use Layer 2 in conjunction with MAC addresses 

A CLIENT and a SERVER must use the same type of protocol to communicate using the OSI Model


Protocol Data Unit

Different layers of the OSI Model have different types of what is known as Protocol Data Units (PDU)

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