Which OSI layer is responsible for establishing, managing, and terminating sessions?

The OSI model consists of seven layers, each with distinct responsibilities. Layer 5, known as the Session Layer, is specifically designed to manage sessions between applications. This involves establishing connections, maintaining them during data exchanges, and ultimately terminating them when the communication is complete.

The Session Layer plays a crucial role in session control, ensuring that sessions are coordinated without issues such as data loss or misalignment. It provides services to manage dialogue control, allowing communication in different modes such as half-duplex or full-duplex, and it sets up checkpoints for data to ensure the integrity and sequence of the communication.

While other layers have their respective functions—such as Layer 3 which deals with routing and forwarding of packets, and Layer 4 which focuses on transport layer functions including reliable delivery and flow control—the specific task of session establishment and management is distinctly handled by Layer 5. This is what makes the answer correct and highlights the unique function of the Session Layer within the OSI model framework.