Which device is described as a communications hardware device that facilitates the transmission of data?

• A. Modem
• B. Router
• C. Switch
• D. Firewall

Answer: (A)

The device described is the modem. Its job is to convert digital data from a computer into signals that can travel over a communications medium (like a phone line or cable) and then convert signals received from that medium back into digital data for the computer. This modulation and demodulation of signals is what makes data transmission over physical media possible, especially over traditional access technologies to reach an ISP. A router, by contrast, directs packets between networks; a switch connects devices within a local network; and a firewall filters and controls traffic for security. None of those primarily convert between digital data and transmission signals, which is why the modem is the best fit here.