Which device serves as an interface to connect networks that use different protocols and can act as a gateway between them?

• A. Switch
• B. Bridge
• C. Modem
• D. Gateway

Answer: (D)

When networks use different protocols, a device that can interface between them and move data across those boundaries is needed. This role is filled by a gateway, which connects distinct networks and can translate or route traffic between them, enabling communication even when the underlying protocols don’t match. A gateway is commonly the device that links a local network to the Internet, handling the protocol differences and directing data toward its destination.

In contrast, a switch stays within a single network and forwards frames based on MAC addresses; it doesn’t translate between different protocols. A bridge connects two segments of the same network and also operates within a single protocol family. A modem converts digital signals for transmission over telephone lines and provides access to an external network, rather than interconnecting networks with different protocols.