Sizing the IPv4 Plan: /23 Server Room, No Overlap

300-420 By islever Editorial Last updated

Create structured addressing plans for IPv4 and IPv6

Short answer

B A /23 (512 addresses) fits the 500-host server room; the plan also sizes the remote (/25) and access (/27) sites without overlap, maximizing usable subnets.

Question

Refer to the exhibit. An architect is designing an IPv4 plan using the 172.16.0.0/16. The design must maximize the number of subnets while meeting these requirements: • 500 hosts within the server room • 100 hosts at the remote site • 25 hosts at the access site Which plan must the architect choose? - Exhibit: Sizing the IPv4 Plan: /23 Server Room, No Overlap
  1. Server room 172.16.8.0/21
  2. Server room 172.16.2.0/23 Correct Answer
  3. Server room 172.16.2.0/23
  4. Server room 172.16.4.0/22

Key Takeaways

Pick the smallest prefix that holds the host count: 500 to /23, 100 to /25, 25 to /27. Then verify no overlap. B is the only option that satisfies all three without overlap.

For 172.16.0.0/16, the 500-host server room needs a /23 (512 addresses), the 100-host remote site a /25 (128), and the 25-host access site a /27 (32). Option B allocates these without overlap, meeting capacity while maximizing the number of available subnets.

Common mistake: Picking A (server /21) or D (server /22): those waste addresses and/or overlap the remote/access sites; C under-sizes the remote site (not enough hosts for 100). Only B fits all and stays contiguous.

Expert Analysis

Why the Answer Is Correct

B is correct. The server room needs 500 hosts, so a /23 (512 addresses) is the right size; B also sizes the remote site (100 hosts) and access site (25 hosts) without overlapping, maximizing usable subnets within 172.16.0.0/16.

Why the Other Options Are Wrong

A (/21 server) and D (/22 server) waste addresses and overlap the remote/access allocations. C uses a /23 for the server but under-sizes the remote site, leaving it unable to hold 100 hosts. Only B meets every requirement.

Community Comment Notes

The vote is B (100). Commenters confirm /23 gives 512 for the server room, /25 for the remote site, and /27 for the access site, with no overlap.

Community Votes

B
100%

100% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 4 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 4

  1. PicoOstrava 👍 3 Answered B
    Option B: Server room: 172.16.2.0/23 (provides 512 IPs — good for 500 hosts). Remote site: 172.16.4.128/25 (provides 128 IPs — good for 100 hosts). Access site: 172.16.5.32/27 (provides 32 IPs — good for 25 hosts). This option meets all the requirements and is very efficient in terms of IP address allocation
  2. muffedtrims 👍 2 Answered B
    A-incorrect, remote and access overlap B-correct, maximizes subnets available without overlap and provides each site enough hosts C-incorrect, not enough hosts at remote site D-incorrect, remote and access sites overlap
  3. 935608e 👍 2 Answered B
    B is the only one that makes sense -> 23 -> 512, 25 ->128 and 27 ->32
  4. Swiz005 👍 3
    How about B?

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