At the network layer, which device is used to connect networks that may use…

Concept

An internetwork links distinct packet-switched networks. A router operates at the network layer: it examines the destination network address, selects a next hop, and forwards the packet through an appropriate interface.

Because routing acts above the link layer, the incoming and outgoing interfaces may use different link technologies. Link-layer devices instead forward frames within or between compatible LAN segments.

Application

The item asks for the network-layer device that connects networks even when their underlying link technologies differ. That role is performed by a router.

Contrast

• A repeater regenerates and retimes signals on a physical link at the physical layer.

• A switch forwards frames between ports in a local link-layer network, generally on the basis of MAC addresses.

• A bridge joins or divides LAN segments at the link layer and forwards frames by MAC address.

Cross-check

When an IP packet moves from one link technology to another, the device removes the incoming link-layer frame, makes a routing decision from the IP destination, and encapsulates the packet in a new frame for the outgoing link. This is router behaviour.

Result

The required device is a router.