Which sequence correctly lists the OSI layers from the lowest to the highest?

Which sequence correctly lists the OSI layers from the lowest to the highest?

• A. Physical, Data-Link, Network, Transport, Session, Presentation, Application
• B. Physical, Network, Data-Link, Transport, Session, Presentation, Application
• C. Application, Presentation, Session, Transport, Network, Data-Link, Physical
• D. Data-Link, Physical, Network, Transport, Session, Presentation, Application

Answer: (A)

The main idea being tested is the order of the seven OSI layers from the lowest (closest to hardware) to the highest (closest to the user). The correct sequence is: Physical, Data-Link, Network, Transport, Session, Presentation, Application. Think of it as a stack where each layer builds on the work of the one below it. The physical layer handles raw electrical signals and hardware interfaces. The Data-Link layer frames data for transmission over a local link and adds MAC addressing and error detection. The Network layer moves packets between networks and handles routing and logical addressing. The Transport layer ensures end-to-end delivery, reliability, and proper flow control. The Session layer manages ongoing communications between applications. The Presentation layer takes care of data syntax, encryption, and compression. Finally, the Application layer provides network services directly to the user’s software. If you rearrange these, you’ll run into mismatches. For example, placing the Network layer above the Data-Link layer disrupts the flow of framing and addressing that the Data-Link layer provides. Placing the Application layer lower in the stack ignores how the lower layers support communication for applications. So the only order that correctly reflects how data moves from physical transmission up to user services is the one that starts with Physical and ends with Application.

The main idea being tested is the order of the seven OSI layers from the lowest (closest to hardware) to the highest (closest to the user). The correct sequence is: Physical, Data-Link, Network, Transport, Session, Presentation, Application.

Think of it as a stack where each layer builds on the work of the one below it. The physical layer handles raw electrical signals and hardware interfaces. The Data-Link layer frames data for transmission over a local link and adds MAC addressing and error detection. The Network layer moves packets between networks and handles routing and logical addressing. The Transport layer ensures end-to-end delivery, reliability, and proper flow control. The Session layer manages ongoing communications between applications. The Presentation layer takes care of data syntax, encryption, and compression. Finally, the Application layer provides network services directly to the user’s software.

If you rearrange these, you’ll run into mismatches. For example, placing the Network layer above the Data-Link layer disrupts the flow of framing and addressing that the Data-Link layer provides. Placing the Application layer lower in the stack ignores how the lower layers support communication for applications. So the only order that correctly reflects how data moves from physical transmission up to user services is the one that starts with Physical and ends with Application.