Which protocol belongs to the Transport layer in the TCP/IP model?

Which protocol belongs to the Transport layer in the TCP/IP model?

• A. TCP
• B. IP
• C. ARP
• D. HTTP

Answer: (A)

Think about what the Transport layer does in TCP/IP: it provides end-to-end delivery between applications on different hosts, with reliability, sequencing, and multiplexing via port numbers. TCP fits this role because it offers a reliable, connection-oriented service—acknowledgments, retransmission, ordering, and flow control—to ensure data is delivered correctly between applications. IP, by contrast, lives in the Internet layer and handles routing and addressing but does not guarantee delivery. ARP operates at the local link layer to map IP addresses to MAC addresses. HTTP resides in the Application layer, delivering web content and relying on the transport layer beneath. Therefore,_TCP_ is the protocol that belongs to the Transport layer.

Think about what the Transport layer does in TCP/IP: it provides end-to-end delivery between applications on different hosts, with reliability, sequencing, and multiplexing via port numbers. TCP fits this role because it offers a reliable, connection-oriented service—acknowledgments, retransmission, ordering, and flow control—to ensure data is delivered correctly between applications. IP, by contrast, lives in the Internet layer and handles routing and addressing but does not guarantee delivery. ARP operates at the local link layer to map IP addresses to MAC addresses. HTTP resides in the Application layer, delivering web content and relying on the transport layer beneath. Therefore,TCP is the protocol that belongs to the Transport layer.