What layer of the TCP/IP model is responsible for host-to-host communication?

The Transport Layer is responsible for host-to-host communication in the TCP/IP model. This layer's primary function is to ensure that data is transferred reliably and in order between communicating hosts. It achieves this through a variety of protocols such as TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). TCP, for instance, provides connection-oriented communication with mechanisms for error detection and recovery, while UDP offers connectionless communication, focusing on speed over reliability.

By facilitating the delivery of segments (or datagrams in the case of UDP) from one host to another, this layer plays a critical role in determining how data is segmented, transmitted, and reassembled, enabling successful communication across diverse networking scenarios. Thus, its core responsibility of establishing the necessary logical connection for reliable data transfer between hosts underscores its significance in the communication process.