You are troubleshooting a connectivity problem and want to isolate the problem. You suspect that a router on the route to an unreachable network is at fault. Which command would you issue to see…

Question

Options

• Arouter#ping
• Brouter#tracert
• Crouter#show ip route
• Drouter#show cdp neighbors
• Erouter#traceroute

• A
  2% (1)
• C
  2% (1)
• E
  96% (45)

Explanation

traceroute (option E) is the correct Cisco IOS command because it sends probe packets hop-by-hop across a network path and reports the IP address of each router along the way - so when packets stop being returned, you've identified the exact router or link where connectivity fails.

Why the distractors are wrong:

• A (ping) - only tells you if a destination is reachable, not where the path breaks
• B (tracert) - this is the Windows command-line equivalent; on a Cisco router, it won't work (the IOS command is traceroute)
• C (show ip route) - shows the local router's routing table only, not the path packets take across the network
• D (show cdp neighbors) - reveals directly connected Cisco devices, but gives no insight into end-to-end path reachability

Memory tip: Think "traceroute = trace the route." On Windows you shorten it to tracert; on Cisco IOS you spell it out: traceroute. The key distractor trap on this exam is B - don't confuse the Windows tool name with the IOS command name.

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