Transport Layer Protocol in Internet

The transport layer is the fourth layer of the OSI model and is responsible for the delivery of data between hosts on a network. It provides end-to-end communication services, ensuring that data packets are correctly delivered from the source to the destination. There are two commonly used transport layer protocols in the internet: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

TCP (Transmission Control Protocol)
TCP is a connection-oriented protocol that provides reliable, ordered, and error-checked delivery of data packets over an IP network. It establishes a connection between the sender and receiver before data transmission and guarantees that packets arrive in the correct order. It also implements mechanisms for flow control and congestion control to ensure efficient data transfer. TCP is widely used in applications that require reliable and error-free data transmission, such as web browsing, email, file transfer, and remote login.

UDP (User Datagram Protocol)
UDP is a connectionless protocol that provides a lightweight and best-effort delivery of data packets over an IP network. It does not establish a connection before data transmission and does not guarantee that packets arrive in order or without errors. UDP is often used in applications that require minimal delay and can tolerate some packet loss, such as real-time streaming, online gaming, and DNS (Domain Name System) queries.

Both TCP and UDP
Both TCP and UDP are transport layer protocols used in the internet. They have different characteristics and are suitable for different types of applications. TCP offers reliability and error checking, while UDP provides lower latency and less overhead. The choice between TCP and UDP depends on the specific requirements of the application. For example, if data integrity and order are crucial, TCP is preferred. On the other hand, if low latency and minimal overhead are more important, UDP is chosen.

In conclusion, TCP and UDP are the two transport layer protocols used in the internet, each serving different purposes based on the requirements of the application. Therefore, the correct answer is option (c) - Both (a) and (b).