Which transport layer protocol is connection-oriented?

The Transmission Control Protocol (TCP) is a connection-oriented transport layer protocol, which establishes a reliable connection between two devices before transmitting data. This means that TCP ensures that data is delivered in the correct order and without errors, providing a set of mechanisms for error-checking, flow control, and congestion control.

When a TCP connection is initiated, it undergoes a process known as the three-way handshake, where the sender and receiver exchange packets to establish a connection. This process ensures that both ends are ready to communicate and that the parameters of the connection are agreed upon. Once the connection is set up, TCP guarantees that all data packets sent by the sender are received by the receiver, and if any packets are lost or received in the wrong order, TCP can request retransmission of those packets.

In contrast, User Datagram Protocol (UDP) is a connectionless protocol that does not establish a connection before data transfer, nor does it guarantee delivery or order. Internet Control Message Protocol (ICMP) is primarily used for sending error messages and operational information about network conditions; it is not a transport layer protocol for data transfer. Dynamic Host Configuration Protocol (DHCP) is used for assigning IP addresses to devices on a network and works at the application layer