100-150 Question 85
Single answerA network administrator is tasked with configuring IPv6 addressing for a new subnet. The administrator assigns the subnet prefix as 2001:0db8:abcd:0012::/64. Which of the following statements about the IPv6 prefix format is correct?
- A
The prefix indicates the first 64 bits are used for the network portion, and the remaining 64 bits are for the host portion.
- B
The prefix indicates the first 48 bits are used for the network portion, and the remaining bits are for subnetting and hosts.
- C
The double colon (::) means the address is invalid since it skips too many zeroes.
- D
The prefix length of /64 is not recommended for IPv6 and should be changed to /128.
Show answer and explanation
Correct answer: A
Explanation
The IPv6 address 2001:0db8:abcd:0012::/64 uses the standard representation and prefix length for IPv6 subnetting. The /64 prefix length indicates that the first 64 bits are designated for the network portion, while the remaining 64 bits are available for host addressing. This is the most common configuration in IPv6 networks and is recommended for ease of subnetting and device configuration.
- A. Correct.
Correct. In an IPv6 address with a /64 prefix, the first 64 bits are used for the network portion, and the remaining 64 bits are for the host portion, commonly used in IPv6 networks.
- B. Incorrect.
Incorrect. A /48 prefix would indicate the first 48 bits are used for the network portion, which is not the case here. Subnetting and host allocation depend on the prefix length.
- C. Incorrect.
Incorrect. The double colon (::) is valid in IPv6 and is used to represent contiguous zeroes within the address.
- D. Incorrect.
Incorrect. A /64 prefix is standard and recommended in IPv6 for most subnet configurations. A /128 prefix is generally used for specific purposes, such as loopback addresses.