An organization is designing the IP allocation of a new site. It currently has 12 separate IP segments. Each segment must be /24, accommodate 25% of growth, and be easily summarized. Which…

The correct answer is C. /20. Start with the current requirement: 12 segments of /24. Apply 25% growth: 12 × 1.25 = 15 segments needed. To support 15 /24 networks within a single summarizable block, you need the next power of 2 that is ≥ 15, which is 16 (2^4). A /20 prefix contains exactly 16 /24 subnets…

Advanced Addressing and Routing Solutions

Question

An organization is designing the IP allocation of a new site. It currently has 12 separate IP segments. Each segment must be /24, accommodate 25% of growth, and be easily summarized. Which summarized IP block can be subnetted to meet these requirements?

Options

A/18
B/19
C/20
D/21

How the community answered

(47 responses)

A
9% (4)
B
21% (10)
C
66% (31)
D
4% (2)

Explanation

Start with the current requirement: 12 segments of /24. Apply 25% growth: 12 × 1.25 = 15 segments needed. To support 15 /24 networks within a single summarizable block, you need the next power of 2 that is ≥ 15, which is 16 (2^4). A /20 prefix contains exactly 16 /24 subnets (because /24 - /20 = 4 bits, and 2^4 = 16). This satisfies both the growth requirement (16 ≥ 15) and the easy summarization requirement (a single /20 summarizes all 16 /24s). Option A (/18) provides 64 /24 subnets - far more than needed and wasteful. Option B (/19) provides 32 /24 subnets - more than needed. Option D (/21) provides only 8 /24 subnets - not enough to accommodate even the current 12 segments.

Topics

#IP addressing#subnetting#route summarization#growth planning

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