Which protocol is responsible for the actual delivery of data over a network?

The Transmission Control Protocol (TCP) is responsible for the reliable delivery of data over a network. It ensures that data packets are delivered in the correct order and without errors. TCP establishes a connection between the sender and receiver through a process called handshaking, allowing for acknowledgment of receipt and retransmission of lost packets. This reliability is crucial for applications where data integrity and order are vital, such as web browsing, email, and file transfers.

While other protocols mentioned each play important roles, they serve different functions. User Datagram Protocol (UDP) is utilized for applications that prioritize speed over reliability, such as live video streaming, where occasional data loss is acceptable. Internet Protocol (IP) takes care of routing packets across the network but does not guarantee delivery or order. File Transfer Protocol (FTP) is used for transferring files but relies on TCP under the hood to ensure those transfers occur reliably. Thus, TCP stands out as the protocol that ensures the actual delivery of data with the necessary reliability and integrity.