Which of the following is a correct sequence of different layers of Open System Interconnection (OSI) model?

The Open Systems Interconnection (OSI) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven distinct abstraction layers. The correct sequence, starting from the lowest layer (Layer 1) which deals with the physical hardware, to the highest layer (Layer 7) which interacts with the user application, is: Physical, Data Link, Network, Transport, Session, Presentation, and Application. This order ensures a structured flow of data, where each layer serves the layer above it and is served by the layer below it. Option D correctly lists these seven layers in ascending order.

A. This option incorrectly swaps the Session and Presentation layers. The Session layer (Layer 5) must precede the Presentation layer (Layer 6).
B. This option incorrectly orders the lower layers. The Data Link layer (Layer 2) should come before the Network layer (Layer 3).
C. This option, when read from top to bottom, incorrectly orders the middle layers. The Session layer (Layer 5) should precede the Transport layer (Layer 4).

1. International Organization for Standardization. (1994). ISO/IEC 7498-1:1994 Information technology — Open Systems Interconnection — Basic Reference Model: The Basic Model. Section 7, "Detailed description of the seven layers of the OSI Reference Model," explicitly lists the layers in the following order: Physical, Data-Link, Network, Transport, Session, Presentation, and Application.

2. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. In Chapter 1, Section 1.5.2, "The OSI Model," the text describes the seven-layer model, stating, "The seven layers of the OSI reference model are: application layer, presentation layer, session layer, transport layer, network layer, data link layer, and physical layer." This lists the layers from top to bottom, which corresponds to the bottom-to-top order presented in the correct answer.

3. Stallings, W. (2016). Foundations of Modern Networking: SDN, NFV, and Cloud Computing. Addison-Wesley Professional. Chapter 2, Section 2.1, "The OSI Model," presents a table (Table 2.1) and a figure (Figure 2.2) that clearly illustrate the seven layers in the correct sequence: Physical, Data Link, Network, Transport, Session, Presentation, Application.