It can be both because the data link layer is responsible for communications between adjacent network nodes and hubs and switches operate at the data link layer.
The data link layer is logically divided into two sub-layers, The Media Access Control (MAC) Sub-layer and the Logical Link Control (LLC) Sub-layer.
The MAC Sub-layer is responsible for addressing on the Local Area Network.
The MAC Sub-layer is also responsible for determining when nodes on a Local Area Network are allowed to transmit.
LLC Sub-layer is responsible for synchronizing frames, error checking, and flow control.
Data Link Layer includes ethernet, wi-fi, frame relay, ATM, and PPP.
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