200-301 Question 259
Single answerA network administrator is troubleshooting connectivity between two devices on different subnets. The administrator pings the IP address of the default gateway on one of the devices and receives a 'Destination Host Unreachable' response. What is the most likely cause of this issue?
- A
The default gateway is configured incorrectly on the device.
- B
The interface on the router connected to the subnet is administratively down.
- C
The device does not have a valid IP address assigned.
- D
The device's ARP cache is full and cannot resolve the MAC address of the default gateway.
Show answer and explanation
Correct answer: B
Explanation
A 'Destination Host Unreachable' message typically indicates a Layer 3 issue, such as the router interface being down or not reachable. In this scenario, the most probable cause is that the interface on the router (default gateway) is administratively down, preventing communication between the device and the router.
- A. Incorrect.
Incorrect default gateway configuration would result in packets being misrouted, but it would not specifically lead to a 'Destination Host Unreachable' response.
- B. Correct.
If the router's interface connected to the subnet is administratively down, the device will not be able to communicate with the default gateway, leading to a 'Destination Host Unreachable' message.
- C. Incorrect.
An invalid IP address assignment would prevent communication, but it would not directly generate a 'Destination Host Unreachable' response when pinging the default gateway.
- D. Incorrect.
An ARP cache issue might cause delays or failures in communication, but it is unlikely to be the cause of a 'Destination Host Unreachable' response in this scenario.