Implementation Manager (IM) Specialist CHTS Practice Test

Which layer is NOT part of the core functionalities of the OSI Model?

1. Application Layer

2. Session Layer

3. Protocol Layer

4. Datalink Layer

The correct answer is: Protocol Layer

The correct choice identifies the Protocol Layer as not being part of the core functionalities of the OSI Model. The OSI Model is structured into seven layers—Application, Presentation, Session, Transport, Network, Datalink, and Physical—each with specific roles and responsibilities in data communication. The Application Layer is responsible for providing network services directly to end-users and applications. The Session Layer manages sessions, or connections, between applications, ensuring they can communicate effectively. The Datalink Layer provides node-to-node data transfer and handles error correction from the Physical Layer. In contrast, the term "Protocol Layer" is not an officially recognized layer within the OSI Model framework. While protocols are indeed crucial for communication between layers (such as TCP for the Transport Layer), the OSI Model itself does not specify a distinct "Protocol Layer." Therefore, the identification of the Protocol Layer as not being part of the core functionalities aligns with an understanding of the OSI framework's defined structure.