OSI Model: Understanding the Seven Layers

The Seven Layers of the OSI Model

Question

The OSI model is the most common networking model used in the industry.

Applications, network functions, and protocols are typically referenced using one or more of the seven OSI layers.

Of the following, choose the two best statements that describe the OSI layer functions.

Each correct answer represents a complete solution.

Choose two.

Answers

Explanations

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A. B. C. D.

DC.

The Open Systems Interconnection (OSI) model is a conceptual framework that describes the functions of a communication system. It is composed of seven layers, each of which performs specific functions in the communication process.

A. This statement is incorrect. Layers 1 and 2 deal with the physical and data link layers of the model, respectively. Layer 1 deals with physical connectivity, while Layer 2 deals with data encapsulation and framing.

B. This statement is also incorrect. Layers 1 through 3 deal with the physical, data link, and network layers of the model, respectively. Layer 4 is the transport layer, which deals with end-to-end communication between applications, and Layers 5 through 7 are the session, presentation, and application layers, respectively.

C. This statement is partially correct. Layers 5 through 7 deal with the session, presentation, and application layers, respectively, which include functions such as data formatting and session control.

D. This statement is the best description of the functions of the OSI model. Layers 1 through 4 deal with the physical, data link, network, and transport layers of the model, respectively. These layers define the end-to-end functions of data, including physical connectivity, encapsulation, IP addressing, and error recovery.

In summary, the two best statements that describe the OSI layer functions are:

  1. Layers 1, 2, 3, and 4 deal with physical connectivity, encapsulation, IP addressing, and error recovery. These layers define the end-to-end functions of data.

  2. Layers 5, 6, and 7 focus on the network application, which includes data formatting and session control.