In the TCP/IP model, which layer corresponds to the OSI Session and Presentation layers?

• A. Application layer.
• B. Transport layer.
• C. Network layer.
• D. Data Link layer.

Answer: (A)

In TCP/IP, the Session and Presentation functions aren’t separate layers; they’re handled within the Application layer. The Application layer covers high-level protocols used by software and includes how data is represented (encoding/formatting) and how sessions or dialogs are managed within those protocols. For instance, application protocols like HTTP, FTP, or DNS perform their own session handling and data representation needs, and security or encryption (like TLS) is implemented at this layer as part of the application’s communication. The Transport layer focuses on end-to-end delivery, reliability, and ordering; the Network layer handles routing and addressing; and the Data Link layer manages access to the physical network. So, the OSI Session and Presentation responsibilities map to the Application layer in TCP/IP.