Which TCP/IP layer is responsible for end-to-end transport of data and includes TCP and UDP?

• A. Application Layer
• B. Transport Layer
• C. Network Layer
• D. Network Interface Layer

Answer: (B)

End-to-end data transport across a network is handled by the Transport layer. This layer sits between the Internet Protocol, which handles addressing and routing, and the applications that generate or receive data. It provides the means to deliver data from one process on a host to the corresponding process on another host, using port numbers to identify those processes and allow multiple conversations to share a single connection. The Transport layer offers two services: a reliable, connection-oriented service via TCP, which ensures data arrives correctly and in order, and a lightweight, connectionless service via UDP, which aims for lower latency at the cost of reliability. The other layers don’t perform end-to-end transport: the Application layer defines protocols for specific programs (like HTTP or FTP) that use the transport layer; the Network layer handles routing and IP addressing; the Network Interface layer covers the actual physical transmission on the network media. So the Transport layer is the one responsible for end-to-end transport and for providing TCP and UDP.