Which Data-Link Sublayer Performs Medium-Dependent Circuit Functions?

In the classic data link layer decomposition, the layer is split into sublayers so that responsibilities can be separated by what they depend on. The sublayer that performs circuit/media-dependent functions (i.e., functions that vary with the kind of transmission medium) is the Media Access Control sublayer. This is because MAC is responsible for controlling access to the physical medium and framing/handling at the boundary where the medium type matters.

Therefore, for the question “Which sublayer of the information link layer performs circuit functions that depend on the kind of medium?”, the correct option is:

(i) Media access control sublayer.

Mermaid: data link layer responsibilities

Key terms for this question:

• Data Link Layer
• Media Access Control (MAC)
• Logical Link Control (LLC)
• Network Interface Control

Note: The options list “network interface control sublayer,” but in the standard data-link sublayer discussion, the medium-dependent part is attributed to MAC, while the medium-independent part is attributed to LLC.

Why MAC (not LLC) is medium-dependent

• MAC must handle how devices share and use the underlying physical medium (e.g., contention rules, medium-specific framing/interaction requirements). That makes its behavior dependent on medium characteristics.
• LLC is designed to provide a consistent interface (link services) to higher layers regardless of the underlying medium, making it medium-independent in the classic view.

Key terms:

• Frame
• Access control
• Medium independence
• Adjacent node delivery