When an application is sending data to a distant computer, what process occurs on the sending node?

The correct process that occurs on the sending node when an application is sending data to a distant computer is encapsulation. This involves wrapping the data being sent into a specific format suitable for transmission over the network. Essentially, when an application generates data to be sent, it is not immediately sent as a raw message. Instead, the data must be structured into packets that can be effectively managed and transmitted through the various layers of the network protocol stack.

During encapsulation, the application layer data is packaged into segments and then further wrapped in headers and trailers at each layer of the OSI model. For example, the transport layer adds its own header, and the network layer adds an IP header, which ultimately helps in routing the data through the appropriate paths across the network. This process ensures that the data maintains its integrity and can be properly interpreted by the receiving node.

In contrast, other options refer to processes that do not accurately capture what occurs at the sending node when data is being prepared for transmission. Segmentation is a part of the encapsulation process but refers specifically to breaking data into smaller pieces; de-encapsulation is the reverse process that occurs at the receiving end, and transmission refers to the actual sending of the already encapsulated data over the network.