Which transport-layer protocols are used in TCP/IP?

Which transport-layer protocols are used in TCP/IP?

• A. TCP and UDP
• B. IP and ICMP
• C. HTTP and FTP
• D. SSH and TLS

Answer: (A)

In TCP/IP, the transport layer is where two main protocols live: TCP and UDP. They handle how data is delivered from one host to another, sitting above the IP network layer that routes packets. TCP provides reliable, connection-oriented delivery. It establishes a connection, breaks data into segments, numbers them, and uses acknowledgments and retransmissions to ensure everything arrives in order and intact. It also manages flow control and congestion to prevent overwhelming the receiver or the network. UDP offers a much lighter, connectionless service that sends datagrams without guaranteeing delivery, order, or duplicates. This simplicity keeps overhead low and is ideal for applications like streaming or gaming where occasional data loss is acceptable. Both TCP and UDP also use port numbers to multiplex multiple applications on the same host, enabling different processes to communicate simultaneously. IP and ICMP operate at the network layer, handling routing and error messages rather than end-to-end data delivery. HTTP and FTP are application-layer protocols that rely on the transport layer to move their data, while SSH and TLS are security-related protocols that typically run on top of a transport protocol like TCP rather than forming the transport layer themselves.

In TCP/IP, the transport layer is where two main protocols live: TCP and UDP. They handle how data is delivered from one host to another, sitting above the IP network layer that routes packets. TCP provides reliable, connection-oriented delivery. It establishes a connection, breaks data into segments, numbers them, and uses acknowledgments and retransmissions to ensure everything arrives in order and intact. It also manages flow control and congestion to prevent overwhelming the receiver or the network. UDP offers a much lighter, connectionless service that sends datagrams without guaranteeing delivery, order, or duplicates. This simplicity keeps overhead low and is ideal for applications like streaming or gaming where occasional data loss is acceptable.

Both TCP and UDP also use port numbers to multiplex multiple applications on the same host, enabling different processes to communicate simultaneously.

IP and ICMP operate at the network layer, handling routing and error messages rather than end-to-end data delivery. HTTP and FTP are application-layer protocols that rely on the transport layer to move their data, while SSH and TLS are security-related protocols that typically run on top of a transport protocol like TCP rather than forming the transport layer themselves.