Which layer of the OSI model ensures the error-free transmission of data?

The Data Link Layer (Layer 2 of the OSI model) is responsible for ensuring the error-free transmission of data over the physical connection between two devices. It handles the detection and correction of errors that may occur in the physical layer.

This layer breaks data into frames, adds error-checking information using CRC (Cyclic Redundancy Check), and confirms that each frame is correctly received. If an error is found, it can request retransmission depending on the protocol used (like HDLC or PPP).

In summary, the Data Link Layer ensures reliable communication over a single hop — between devices directly connected to each other.