100-150 Question 81
Single answerYou are troubleshooting an issue where a server cannot communicate with other devices on the same IPv6 network. Upon reviewing the server's IPv6 configuration, you find the following address assigned: 2001:0db8:85a3::8a2e:0370:7334/128. Based on this information, what is the most likely cause of the communication failure?
- A
The IPv6 address has an invalid format and cannot be used.
- B
The prefix length of /128 means the server cannot communicate with other devices.
- C
The IPv6 address is a link-local address and is not routable.
- D
The server is correctly configured, and the issue must be elsewhere on the network.
Show answer and explanation
Correct answer: B
Explanation
An IPv6 address with a /128 prefix length is a host-specific address that does not allow subnetting or communication with other devices by default. This configuration is often used for loopbacks or specific purposes. In this scenario, the server's inability to communicate with other devices is likely due to the overly restrictive /128 prefix length.
- A. Incorrect.
The IPv6 address format is valid. The address follows IPv6 conventions, including the use of double colons (::) to shorten zero segments.
- B. Correct.
A /128 prefix length indicates that this address refers to a single device with no subnet. This prevents communication with other devices unless explicitly configured for that purpose.
- C. Incorrect.
The given IPv6 address is not a link-local address. Link-local addresses typically start with
FE80::. - D. Incorrect.
While the address format is valid, the /128 prefix length is likely the root cause of the communication issue, making this answer incorrect.