200-401 · Question #12
You are a called upon to troubleshoot connectivity problems to a network device on a production floor. You have used ping and traceroute to verify that you cannot connect to the device from the…
The correct answer is C. The device has no IP default gateway. Option C is correct because the device can communicate with hosts on the same local subnet (same switch) but fails to reach the management network - a different subnet. Without a default gateway, the device has no way to forward packets beyond its local segment, so replies to…
Question
You are a called upon to troubleshoot connectivity problems to a network device on a production floor. You have used ping and traceroute to verify that you cannot connect to the device from the management network. The network is 209.165.202.128/27 and the device has been given the IP address 209.165.202.158 and mask 255.255.255.224. You have verified that you can reach the device with your computer connected to the same switch as the device. What could be the cause of this problem?
Options
- AThe device is set to the wrong subnet mask.
- BThe device is set to the wrong IP address.
- CThe device has no IP default gateway.
- DThe device is connected to a switchport in the wrong VLAN.
How the community answered
(61 responses)- A5% (3)
- B25% (15)
- C61% (37)
- D10% (6)
Explanation
Option C is correct because the device can communicate with hosts on the same local subnet (same switch) but fails to reach the management network - a different subnet. Without a default gateway, the device has no way to forward packets beyond its local segment, so replies to management-network requests never arrive.
Why the distractors are wrong:
- A (wrong subnet mask): 255.255.255.224 equals /27, which is exactly the mask for a 209.165.202.128/27 network - it's correct.
- B (wrong IP address): 209.165.202.158 falls within the valid host range (.129–.158) of that /27 subnet - it's a legitimate address.
- D (wrong VLAN): If the device were in the wrong VLAN, you wouldn't be able to reach it even from the same switch; local reachability rules this out.
Memory tip: Think "same switch = same subnet = no gateway needed; different network = must have a gateway." Whenever a device is reachable locally but unreachable remotely, suspect a missing or misconfigured default gateway first.
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