Which device commonly runs routing protocols to discover network paths?

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

Answer: (B)

Routing protocols are used to learn the best paths between different networks. Devices that connect multiple networks and make decisions about where to send packets are routers, and that role is exactly what involves running routing protocols. Routers talk to neighboring routers to share information about network topology and link costs, using protocols like OSPF, EIGRP, or BGP to build up routing tables that guide packets toward their destinations.

A switch, by contrast, mainly forwards frames within a single local network segment using MAC addresses and operates at the data link layer. Some switches can do limited routing if they’re Layer 3 switches, but the typical purpose remains local switching rather than discovering routes across networks. A host is an end device that uses a route to reach other networks but doesn’t run routing protocols. A firewall focuses on filtering and inspecting traffic, not on discovering network paths, though it may route traffic when configured as a gateway in some setups.

So the device that commonly runs routing protocols to discover network paths is the router.