In the OSI model, which layer handles dialog control?

• A. Application
• B. Transport
• C. Session
• D. Network

Answer: (C)

Dialog control is about coordinating the conversation between two application processes, including who talks when and how the dialogue is managed. The Session layer is responsible for establishing, maintaining, and terminating a communication session, and it provides the mechanisms to control the dialogue between end systems—keeping the exchange orderly, managing start/stop of conversations, and inserting synchronization points when needed. This makes it the layer that handles dialog control.

The other layers don’t fit this role as well. The Transport layer focuses on end-to-end data transfer and reliability, the Network layer handles routing and addressing, and the Application layer provides services to user processes. Since dialog control specifically involves coordinating the session and dialogue between applications, the Session layer is the best fit.