Which two protocols operate at the Transport Layer?

TCP provides reliable, connection-oriented communication. It ensures that data reaches the destination in order and without errors. It uses acknowledgments and retransmission mechanisms. TCP is used for important tasks like emails, websites, and file transfers.

UDP provides fast, connectionless communication. It does not check for delivery or errors, making it faster but less reliable. It is useful for applications like video calls, online games, and streaming where speed matters more than accuracy.

Besides TCP and UDP, other Transport Layer protocols include:

• SCTP (Stream Control Transmission Protocol): Combines features of TCP and UDP. It offers reliability like TCP but supports multiple streams of data in one connection. It is often used in telecommunication networks.


• DCCP (Datagram Congestion Control Protocol): Used for real-time applications where timely delivery is more important than reliability, like voice or video streaming. It adds congestion control to UDP-like delivery.

Key Transport Layer functions:

• End-to-end communication


• Segmentation and reassembly of data


• Error checking and flow control


• Reliable or fast transmission based on the protocol

Conclusion: The correct answer is TCP and UDP. These are the two main protocols used at the Transport Layer, but understanding SCTP and DCCP helps you go deeper into networking concepts, especially for interviews and advanced exams.