Which layer is associated with providing services to the application layer and receiving services from the network layer?

• A. Layer 4 Transport
• B. Layer 5 Session
• C. Layer 6 Presentation
• D. Layer 7 Application

Answer: (A)

The transport layer is the one that sits between the network layer below and the application layer above, handling end-to-end data delivery. It takes data from the network layer, adds the necessary control information (like sequencing, error checking, and flow control), and delivers it to the appropriate application process. It also provides services to the application by offering reliable delivery or best-effort delivery through protocols like TCP and UDP, and it uses port numbers to ensure data goes to the correct application. In short, the transport layer bridges the network and the application, enabling apps to communicate without worrying about how the data is transmitted across the network.