At which OSI layer does a hub operate?

A hub operates at Layer 1 of the OSI model, which is the Physical layer. This layer is responsible for the actual transmission of raw bitstreams over various physical mediums, such as cables or fiber optics. Hubs take incoming data signals and broadcast them to all ports, regardless of the destination, without any form of data interpretation or filtering. This means that they do not process or analyze the data being sent, and they only re-transmit signals to ensure connectivity in a network.

Understanding that the hub does not work with data packets or frames, which are managed at higher layers, highlights its function strictly within the physical transmission of data. Other options represent layers where more complex operations, such as error detection, packet forwarding, or session management, occur, which are beyond the capabilities of a simple hub.