A company has been given a Class C address to be utilized for all devices. The company has several subnets and the largest subnet has 15 hosts. Which of the following represents the MINIMUM CIDR…

The correct answer is B. /27. To find the minimum (most efficient/smallest) subnet that still fits 15 hosts, calculate usable hosts for each option using the formula 2^n - 2 (where n = host bits): /26 = 6 host bits → 2^6 - 2 = 62 usable hosts (works, but wastes addresses); /27 = 5 host bits → 2^5 - 2 = 30…

Networking concepts

Question

A company has been given a Class C address to be utilized for all devices. The company has several subnets and the largest subnet has 15 hosts. Which of the following represents the MINIMUM CIDR notation of this subnet mask?

Options

A/26
B/27
C/28
D/29

How the community answered

(49 responses)

A
2% (1)
B
82% (40)
C
10% (5)
D
6% (3)

Explanation

To find the minimum (most efficient/smallest) subnet that still fits 15 hosts, calculate usable hosts for each option using the formula 2^n - 2 (where n = host bits): /26 = 6 host bits → 2^6 - 2 = 62 usable hosts (works, but wastes addresses); /27 = 5 host bits → 2^5 - 2 = 30 usable hosts (works and is the smallest that fits 15); /28 = 4 host bits → 2^4 - 2 = 14 usable hosts (NOT enough for 15 hosts); /29 = 3 host bits → 2^3 - 2 = 6 usable hosts (far too small). The minimum CIDR that accommodates 15 hosts without falling short is /27, providing 30 usable addresses.

Topics

#subnetting#CIDR notation#Class C#IP addressing

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