What is the main function of the Transport Layer?

The primary function of the Transport Layer is to encapsulate application data into segments. This process involves taking the data generated by an application layer and preparing it for transmission over the network. The Transport Layer adds headers to these segments, which contain important information such as source and destination ports, sequence numbers, and error-checking mechanisms. This segmentation ensures that data can be transmitted efficiently and reliably between hosts in a communication network.

By segmenting data, the Transport Layer facilitates flow control and error recovery, providing reliable or unreliable delivery options depending on the transport protocol used (such as TCP for reliable transmission or UDP for faster but potentially less reliable transmission). This encapsulation also allows the higher layers of the protocol stack to remain agnostic about the details of data transmission, focusing instead on the content and structure of the data itself.

The other options pertain to functions that are not primarily within the scope of the Transport Layer. Data routing is handled by the Network Layer, managing physical connections is the responsibility of the Physical Layer, and connecting to the internet involves several layers working in conjunction, including the Network and Link Layers, among others.