N10-009 · Question #279
A network engineer implements a 192.168.100.0/25 subnet for a building without obtaining sizing requirements. It is later determined that the building will house 700 people. Which of the following…
The correct answer is A. 255.255.252.0. To efficiently support 700 hosts, a subnet mask of 255.255.252.0 provides 1022 usable host addresses, which is the smallest mask that accommodates the requirement.
Question
A network engineer implements a 192.168.100.0/25 subnet for a building without obtaining sizing requirements. It is later determined that the building will house 700 people. Which of the following subnet masks will most efficiently support that number of people?
Options
- A255.255.252.0
- B255.255.254.0
- C255.255.255.0
- D255.255.255.128
How the community answered
(21 responses)- A81% (17)
- B5% (1)
- C5% (1)
- D10% (2)
Why each option
To efficiently support 700 hosts, a subnet mask of 255.255.252.0 provides 1022 usable host addresses, which is the smallest mask that accommodates the requirement.
A subnet mask of 255.255.252.0 corresponds to a /22 CIDR prefix, which allows for 2^(32-22) - 2 = 1024 - 2 = 1022 usable host addresses, efficiently supporting 700 people.
A subnet mask of 255.255.254.0 corresponds to a /23 CIDR prefix, providing only 2^9 - 2 = 510 usable host addresses, which is insufficient for 700 people.
A subnet mask of 255.255.255.0 corresponds to a /24 CIDR prefix, providing only 2^8 - 2 = 254 usable host addresses, which is insufficient for 700 people.
A subnet mask of 255.255.255.128 corresponds to a /25 CIDR prefix, providing only 2^7 - 2 = 126 usable host addresses, which is insufficient for 700 people.
Concept tested: Subnetting for host requirements
Source: https://learn.microsoft.com/en-us/training/modules/network-fundamentals/networking-basics#subnetting
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