CISSP Practice Exam 2025 – Complete Prep Guide

The OSI model, which stands for Open Systems Interconnection model, is best described as a network model with seven layers. It was developed by the International Organization for Standardization (ISO) to facilitate communication and interoperability between different systems and networks. Each of the seven layers has a specific role and set of functions that help manage the complexities of network communication.

These seven layers are:

1. **Physical Layer**: This layer deals with the physical connection between devices, including cables, switches, and electrical signals.

2. **Data Link Layer**: Responsible for node-to-node data transfer and error detection/correction from the physical layer.

3. **Network Layer**: This layer handles the routing of data packets between devices across different networks.

4. **Transport Layer**: Ensures complete data transfer and provides error recovery and flow control.

5. **Session Layer**: Manages sessions between user applications, establishing and terminating connections.

6. **Presentation Layer**: Translates data between the application layer and the network, ensuring that data is presented in a usable format.

7. **Application Layer**: This is the layer closest to the end user and facilitates interaction between software applications and the underlying network.

The significance of the OSI model lies