Question

For the following Unique Local Network ID:

...what are the first and last subnets available to use with the CIDR notation?
a) fc00::/7 and fdff::/7
b) fc00::/8 and fdff::/8
c) fc00::/8 and fdff::/8
d) fc00::/7 and fdff:ffff:ffff:ffff::/65

Answer 1

The correct answer is option d, which specifies the first and last subnets available in the Unique Local IPv6 address prefix as fc00::/7 and fdff:ffff:ffff:ffff::/65. Options a, b, and c do not provide the correct range or CIDR notation for the last subnet.

Step-by-step explanation:

The student is asking about the first and last subnets available for a Unique Local IPv6 address prefix which lies within the fc00::/7 range. Let's clarify each option given:

• Option a: fc00::/7 and fdff::/7 - Here, the prefixes are correct, but the CIDR notation is not. The CIDR notation should be more specific to pinpoint the actual subnet.
• Option b: fc00::/8 and fdff::/8 - This option has correct prefixes but incorrect CIDR notation, similar to option a.
• Option c: fc00::/8 and fdff::/8 - This is a repetition of option b and contains the same error.
• Option d: fc00::/7 and fdff:ffff:ffff:ffff::/65 - This option correctly represents the first subnet fc00::/7, and the last subnet is a smaller block within the last /64 of the range, reflecting a more accurately defined end of the range.

Therefore, the correct answer should be d: fc00::/7 and fdff:ffff:ffff:ffff::/65. It's important to remember that while the fc00::/7 range is composed of Unique Local Addresses (ULAs), the specific subnets used should be randomly generated within this range to avoid conflicts in a private network.