Drag and Drop Question An engineer must design an addressing plan for a small business using a single /24 network. Each department must have its own subnet. Drag and drop the subnets from the left ont

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Explanation

The task is to match subnet blocks to departmental host requirements from a single /24 network, ensuring that each selected subnet can accommodate the required number of hosts and that all chosen subnets are non-overlapping.

Approach. To correctly answer this question, the test-taker must calculate the number of usable hosts for each available subnet and then match them to the department requirements while ensuring that the selected subnets do not overlap.

1. Calculate Usable Hosts for Each Subnet Mask:

   • A /29 subnet (2^(32-29) - 2 = 2^3 - 2 = 8 - 2 = 6 usable hosts)
   • A /28 subnet (2^(32-28) - 2 = 2^4 - 2 = 16 - 2 = 14 usable hosts)
   • A /27 subnet (2^(32-27) - 2 = 2^5 - 2 = 32 - 2 = 30 usable hosts)
   • A /26 subnet (2^(32-26) - 2 = 2^6 - 2 = 64 - 2 = 62 usable hosts)

2. Determine Minimum Subnet Size for Each Department:

   • Human Resources (5 hosts): Needs at least 5 hosts, so a /29 subnet (6 usable hosts) is the smallest suitable.
   • Finance (12 hosts): Needs at least 12 hosts, so a /28 subnet (14 usable hosts) is the smallest suitable.
   • Facilities (18 hosts): Needs at least 18 hosts, so a /27 subnet (30 usable hosts) is the smallest suitable.
   • Engineering (32 hosts): Needs at least 32 hosts, so a /26 subnet (62 usable hosts) is the smallest suitable.

3. Match Subnets to Departments, Avoiding Overlap:

   • Human Resources (5 hosts): The only /29 subnet available is 10.1.1.112/29 (range: 10.1.1.112 - 10.1.1.119). Drag 10.1.1.112/29 to '5 hosts for Human Resources'.
   • Engineering (32 hosts): Needs a /26. Available are 10.1.1.0/26 (range: 10.1.1.0 - 10.1.1.63) and 10.1.1.96/26 (range: 10.1.1.96 - 10.1.1.159). If we select 10.1.1.96/26, it would overlap with 10.1.1.112/29 (HR's subnet) and 10.1.1.96/28 (a potential Finance subnet). Therefore, 10.1.1.0/26 is the only viable non-overlapping /26 option. Drag 10.1.1.0/26 to '32 hosts for Engineering'.
   • Facilities (18 hosts): Needs a /27. Available are 10.1.1.16/27 (range: 10.1.1.16 - 10.1.1.47) and 10.1.1.64/27 (range: 10.1.1.64 - 10.1.1.95). 10.1.1.16/27 overlaps with the 10.1.1.0/26 assigned to Engineering. Thus, 10.1.1.64/27 is the correct non-overlapping choice. Drag 10.1.1.64/27 to '18 hosts for Facilities'.
   • Finance (12 hosts): Needs a /28. Available are 10.1.1.8/28 (range: 10.1.1.8 - 10.1.1.23) and 10.1.1.96/28 (range: 10.1.1.96 - 10.1.1.111). 10.1.1.8/28 overlaps with the 10.1.1.0/26 assigned to Engineering. Thus, 10.1.1.96/28 is the correct non-overlapping choice. Drag 10.1.1.96/28 to '12 hosts for Finance'.

Final Correct Matches:

• 5 hosts for Human Resources -> 10.1.1.112/29
• 18 hosts for Facilities -> 10.1.1.64/27
• 32 hosts for Engineering -> 10.1.1.0/26
• 12 hosts for Finance -> 10.1.1.96/28

Common mistakes.

• common_mistake. Common mistakes include:

1. Incorrectly calculating usable hosts: Forgetting to subtract two addresses (network and broadcast) from the total addresses in a subnet leads to overestimating available hosts.
2. Ignoring the non-overlapping requirement: The most critical error is selecting subnets that overlap in their IP address ranges. For example, selecting 10.1.1.0/26 for one department and 10.1.1.16/27 for another would be incorrect as 10.1.1.16/27 is a sub-subnet of 10.1.1.0/26.
3. Choosing a subnet that is too small: Selecting a subnet that does not provide enough usable hosts for the department's requirements.
4. Choosing a subnet that is excessively large: While technically meeting the requirement, choosing a much larger subnet than necessary (e.g., a /26 for 5 hosts) is poor IP address management, although not explicitly 'wrong' according to the prompt's phrasing, it's generally avoided in real-world design and could lead to failure if a more optimal, non-overlapping solution exists for all requirements.
5. Misidentifying network or broadcast addresses: Not correctly determining the start and end IP address for a given CIDR block can lead to misjudging overlaps.

Concept tested. The core concepts tested are IP subnetting, Variable Length Subnet Masking (VLSM), calculation of usable host addresses within a subnet, and the ability to design a non-overlapping IP addressing plan from a given supernet.

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