Which of the following is reliable communication?

In the context of computer networks and telecommunications, “reliable communication” refers to a method of communication where the system guarantees that information (data) sent from one point in the network (e.g., a computer, a phone) to another point is received exactly as it was sent, without loss, error, duplication, or out-of-order delivery. This is achieved through various error-checking, feedback, and correction mechanisms. One common example of reliable communication protocol is TCP (Transmission Control Protocol), widely used over the Internet.

TCP ensures reliable communication by:

1. Establishing a connection between sender and receiver before transmitting data.
2. Requiring the receiver to acknowledge receipt of packets of data. If the sender does not receive an acknowledgment within a certain time frame, it will retransmit the data.
3. Implementing error-checking mechanisms to detect corrupted data. Corrupted data packets are retransmitted.
4. Ensuring data packets are delivered in order, reordering them if necessary.

Other examples of reliable communication methods might include file transfer protocols that verify the integrity of files after they have been transferred or messaging protocols that guarantee message delivery and inform the sender of message status (e.g., sent, delivered, read).

In contrast, not all communication needs to be reliable. For example, protocols like UDP (User Datagram Protocol) do not guarantee delivery, order, or error-free communication but are useful in situations where speed is more critical than absolute reliability (e.g., live video streaming