Which protocol is considered a connectionless Transport Layer protocol?

The User Datagram Protocol (UDP) is recognized as a connectionless Transport Layer protocol. This means that it does not establish a dedicated end-to-end connection before transmitting data. Instead, UDP sends messages, known as datagrams, without needing to confirm whether the recipient is ready to receive data, nor does it create a communication session.

This characteristic allows for faster data transmission since there's minimal overhead involved in the communication process. Because UDP does not require acknowledgments from the receiving end, it is well-suited for applications where speed is preferred over reliability, such as live video streaming or online gaming. In such scenarios, the timely delivery of packets is crucial, and occasional loss of packets is acceptable.

In contrast, other protocols, such as TCP and SCTP, function on a connection-oriented basis where a session is established and maintained throughout the communication process to ensure data integrity and order. ICMP, while recognized as a network-layer protocol primarily for diagnostics and error messaging, does not fit within the Transport Layer frame of protocols. Hence, UDP is the correct identification of a connectionless protocol in this context.