100-140 Question 232
Select 2A network administrator is troubleshooting connectivity issues between two IPv6-enabled devices on a network. They decide to use the 'traceroute6' command to analyze the path taken by the packets. After running the command, they notice that one of the hops displays '***' instead of an IP address. What does this indicate?
- A
The device at that hop is unreachable or not responding to ICMPv6 packets.
- B
The traceroute6 command is not supported on the device running the test.
- C
The hop is using IPv4 and cannot be identified by traceroute6.
- D
The device at that hop is configured to block traceroute6 requests or ICMPv6 packets.
Show answer and explanation
Correct answers: A, D
Explanation
When using traceroute6, '' in the output for a hop indicates an issue with that hop. This could happen if the device is unreachable, not responding to ICMPv6 packets, or deliberately blocking such packets. Traceroute6 relies on ICMPv6 for its functionality, and any disruption in receiving responses from a hop will cause the '' to appear.
- A. Correct.
Correct: '***' indicates that the device at that hop is either unreachable or not responding to ICMPv6 packets, which is required for traceroute6 to function.
- B. Incorrect.
Incorrect: If the traceroute6 command were unsupported on the testing device, the command would not execute at all, rather than displaying '***' for a specific hop.
- C. Incorrect.
Incorrect: Traceroute6 specifically traces IPv6 paths and is unrelated to IPv4 hops. IPv4 devices would not appear on the path traced by traceroute6.
- D. Correct.
Correct: If a device on the route is configured to block ICMPv6 packets (e.g., due to firewall rules), it could prevent traceroute6 from displaying its details, resulting in '***'.