What is a layer 3 networking device that use IP addressing to forward packets between networks?

• A. Router
• B. Switch
• C. Hub
• D. Bridge

Answer: (A)

Layer 3 devices are responsible for moving packets between different networks by using IP addresses. They examine the destination IP in each packet and consult routing tables (and sometimes routing protocols) to decide the best next hop toward the destination, enabling inter-network communication and traversal across subnet boundaries. The device that performs this IP-based inter-network forwarding is a router, which connects multiple networks and handles routing decisions at the network layer.

Why this fits best: routers are designed to route traffic across disparate networks, not just within a single local network. They can connect different IP subnets and determine the optimal path for a packet to reach its destination, even if it requires hopping through multiple networks.

Why the others don’t fit: switches operate at the data link layer and forward frames based on MAC addresses, primarily within the same network or VLAN. Hubs are basic layer 1 repeaters that broadcast signals to all ports without learning addresses. Bridges also work at the data link layer, learning MAC addresses to forward frames between LAN segments but do not route traffic between different networks using IP addresses.