Which function is described as providing synchronization between source and target nodes at the MAC sublayer?

• A. Integrates various physical technologies.
• B. Communicates between the networking software at the upper layers and the device hardware at the lower layers.
• C. Adds Layer 2 control information to network protocol data.
• D. Provides synchronization between source and target nodes.

Answer: (D)

Synchronization between source and target nodes at the MAC sublayer is achieved through the MAC’s timing signals, specifically the preamble and start-of-frame delimiter. The sender transmits a preamble pattern so the receiver can lock its clock to the incoming bit stream, align sampling correctly, and recognize the start of the actual frame with the start-of-frame delimiter. This timing alignment is what lets both ends stay in sync enough to reliably interpret the frame boundaries and data.

Other MAC responsibilities include encapsulation (adding source and destination MAC addresses, EtherType, and FCS) and coordinating access to the shared medium, but they’re not about establishing timing between nodes. So the synchronization function described is the mechanism that aligns transmitter and receiver timing at the MAC sublayer.