Answer:
Traceroute, ping the router
Explanation:
Traceroute: when you traceroute or tracet to a workstation with the suspected router on its path, the output on the screen is a hop count which is amount of time spent on a router. If a router is faulty, the hop count stops on the router before the faulty one.
Ping the router address: every interface on a router has an IP address, so it can be ping. The ping sends five echo packets to the interface, if faulty, it sends a request time out, if not , it sends back a reply. If the ip address of router is not known, ping a workstation on the same path as the router to confirm to deduction.
