100-140 Question 230
Select 2You are troubleshooting connectivity issues in an IPv6-enabled network. To test the reachability of a specific IPv6 address, you decide to use the 'ping6' command from a Linux system. After running 'ping6 2001:db8::1', you receive the following output: 'Destination unreachable: Address unreachable'. Which of the following could be the cause of this issue?
- A
The IPv6 address 2001:db8::1 is not properly configured on the destination device.
- B
The local system does not have an IPv6 default gateway configured.
- C
The local firewall is blocking ICMPv6 Echo Request packets.
- D
There is no route to the destination IPv6 address from the local system.
Show answer and explanation
Correct answers: A, D
Explanation
The 'Destination unreachable: Address unreachable' message in the ping6 output indicates that the local system was unable to deliver packets to the specified IPv6 address. This could be because the destination device does not have the IPv6 address configured (Option 1) or because there is no route to the destination from the local system (Option 4). Other issues, such as a missing default gateway or firewall blocking, would result in different error messages or symptoms.
- A. Correct.
This is a valid explanation for the error. If the IPv6 address is not properly configured on the destination device, it cannot be reached, resulting in the 'Address unreachable' message.
- B. Incorrect.
While a missing IPv6 default gateway could cause connectivity issues, it would typically result in a different error message, such as 'Network unreachable', rather than 'Address unreachable'.
- C. Incorrect.
A local firewall blocking ICMPv6 Echo Request packets would prevent the ping6 command from sending requests, but it would not produce the 'Address unreachable' message.
- D. Correct.
If there is no known route to the destination IPv6 address, the local system cannot deliver packets, leading to the 'Address unreachable' error.