What is the primary function of the Data Link layer?

The primary function of the Data Link layer is framing and addressing. This layer is responsible for packaging data into frames, which are a manageable unit for transmission. Each frame includes both the data being sent and the necessary addressing information, allowing the sender and receiver to understand where the data is coming from and where it needs to go.

Framing is essential because it ensures that the data is organized in a structure that can be easily interpreted by the receiving device. The addressing provided in the frames identifies the specific devices on the same network segment, which is crucial for ensuring that data reaches its intended destination.

While the other options cover various functions associated with networking, they do not pertain to the core responsibilities of the Data Link layer. For instance, routing data across networks is a function that belongs to the Network layer, and establishing session connections pertains to the Session layer. Encrypting data transmissions involves higher-level security protocols and is not a primary role of the Data Link layer.