Which of the following OSI layers does not have a direct counterpart in the TCP/IP model?

In the TCP/IP model, the Presentation layer of the OSI model does not have a direct counterpart. The reason for this is that the functions of the Presentation layer, which include data translation, encryption, and compression, are generally handled by the Application layer in the TCP/IP model.

The TCP/IP model simplifies the architecture compared to the OSI model, combining what the OSI separates into several layers. For example, both the Session and Presentation layers of the OSI are incorporated into the Application layer in the TCP/IP model. This means that while the Application layer deals with application-level protocols and interfaces, it also encompasses the responsibilities that would otherwise be divided among the Session and Presentation layers in the OSI architecture.

This amalgamation highlights the differences in the abstraction levels and complexity of the two models. The layered structure of the OSI is more theoretical and comprehensive, while the TCP/IP model is more pragmatic and widely adopted in real-world implementations.