300-420 Question 7
Single answerYour organization is planning to implement a dual-stack strategy to support both IPv4 and IPv6. The network consists of five departments, each requiring 500 devices to be accommodated in the addressing plan. For IPv4, you have been allocated the 192.168.0.0/22 range, and for IPv6, you have been allocated a /48 prefix (2001:db8:abcd::/48). What is the most appropriate addressing plan to meet the requirements while minimizing wasted addresses?
- A
Use a /25 subnet for each department in IPv4 and a /64 subnet for each department in IPv6.
- B
Use a /24 subnet for each department in IPv4 and a /63 subnet for each department in IPv6.
- C
Use a /23 subnet for each department in IPv4 and a /64 subnet for each department in IPv6.
- D
Use a /27 subnet for each department in IPv4 and a /56 subnet for each department in IPv6.
Show answer and explanation
Correct answer: A
Explanation
The correct addressing plan must balance efficiency and scalability. Using a /25 subnet for IPv4 provides the necessary 500 device support with minimal wasted addresses, as each department will use 128 IPs. For IPv6, a /64 subnet is the standard and recommended size for subnets, ensuring compatibility with modern IPv6 deployments. This approach meets the organization's requirements while adhering to best practices.
- A. Correct.
This is correct. A /25 subnet for IPv4 provides 128 addresses, which is sufficient for the 500 devices required per department. For IPv6, a /64 subnet is the standard recommendation for host subnets, ensuring scalability and compatibility.
- B. Incorrect.
This is incorrect. A /24 subnet for IPv4 provides 256 addresses, which is insufficient for 500 devices. Additionally, a /63 subnet for IPv6 is not a standard practice and is generally reserved for specific use cases.
- C. Incorrect.
This is incorrect. A /23 subnet for IPv4 provides 512 addresses, which meets the requirement but wastes a significant number of unused IPs given the 500-device requirement. A /64 for IPv6 is correct, but the IPv4 inefficiency makes this option less optimal.
- D. Incorrect.
This is incorrect. A /27 subnet for IPv4 provides only 32 addresses, which is far below the required 500 addresses. For IPv6, a /56 is unnecessarily large for a single department in this scenario.