CREST Practitioner Security Analyst (CPSA) 2026 – 400 Free Practice Questions to Pass the Exam

The OSI Model, which stands for Open Systems Interconnection Model, is indeed divided into seven distinct layers, each with its own unique responsibilities. These layers are:

1. **Physical Layer** - This layer deals with the physical connection between devices and the transmission of raw binary data over a physical medium.

2. **Data Link Layer** - Responsible for node-to-node data transfer and error detection and correction.

3. **Network Layer** - Manages packet forwarding, including routing through different routers.

4. **Transport Layer** - Ensures complete data transfer and maintains data integrity, providing either reliable or unreliable delivery.

5. **Session Layer** - Manages sessions between applications, controlling the dialog and synchronization between them.

6. **Presentation Layer** - Translates data between the format required by the application layer and the format used by the network; it may include encryption and compression.

7. **Application Layer** - Closest to the end user, this layer interacts directly with software applications to provide network services.

Each layer serves a specific purpose and allows for modular engineering, which simplifies the design and implementation of networks as changes can be made to a layer without affecting others. This seven-layer approach is a fundamental concept in networking and plays a critical