What device is responsible for inspecting the contents of Ethernet protocol data and directing it to a specific system?

The device that inspects the contents of Ethernet protocol data and directs it to a specific system is a switch. A switch operates at the data link layer (Layer 2) of the OSI model and uses MAC addresses to determine where to forward data packets. When data arrives at a switch, it examines the destination MAC address in each Ethernet frame and then sends that frame only to the port that corresponds to the device with that specific MAC address. This method significantly reduces network congestion, as data is sent only to the intended recipient rather than being broadcast to all devices connected to the network.

In contrast, a hub operates at a much simpler level and merely broadcasts data to all connected devices, regardless of the intended recipient, which can lead to increased traffic and reduced performance. A router, while also a crucial device in networking, primarily functions at the network layer (Layer 3) and is responsible for directing data between networks rather than managing MAC addresses or switching frames on the same network. A modem connects your local network to the Internet by modulating and demodulating signals but does not perform the functions of inspecting and directing Ethernet data locally. Thus, the switch is the most accurate choice for the role described in the question.