Transport Layer Protocols and Functions in Networking Practice Test

When an application needs data to arrive intact and in the same order as it was sent, the transport layer uses a protocol that provides reliable, connection-oriented delivery. That protocol is TCP. It establishes a connection, numbers data segments, and uses acknowledgments and retransmission to recover any lost data. The receiving side reassembles the data stream in the correct order, and flow control plus congestion control manage how fast data is sent. These features together guarantee reliability and in-order delivery, which is essential for applications like web browsing, file transfer, and email.

UDP, in contrast, does not guarantee delivery or order and is used for time-sensitive or lightweight tasks where speed matters more than reliability. ICMP operates at the network layer to report errors and diagnose issues, not for delivering application data. ARP is a link-layer protocol used to map IP addresses to MAC addresses, not a transport mechanism.