SK0-004 · Question #195
A server administrator is setting up a new set of hosts for an application that requires communication between all the hosts on a dedicated private subnet. Initially, the configuration consists of…
The correct answer is B. /26. To support 48 hosts with the fewest wasted addresses, the /26 prefix is the smallest subnet that still fits all required hosts.
Question
A server administrator is setting up a new set of hosts for an application that requires communication between all the hosts on a dedicated private subnet. Initially, the configuration consists of four hosts and is expected to grow to 48 total as the application is implemented for the entire company. When configuring the private subnet, which of the following CIDR netmasks would allow for the full number of hosts once the application is fully in production with the least number of unused addresses allocated?
Options
- A/25
- B/26
- C/27
- D/28
How the community answered
(41 responses)- A15% (6)
- B46% (19)
- C7% (3)
- D32% (13)
Why each option
To support 48 hosts with the fewest wasted addresses, the /26 prefix is the smallest subnet that still fits all required hosts.
A /25 subnet provides 126 usable addresses, which far exceeds the 48-host requirement and wastes significantly more address space than necessary.
A /26 subnet yields 2^6 - 2 = 62 usable host addresses, which is the smallest block that can accommodate the maximum 48 hosts. This leaves only 14 unused addresses, minimizing waste while meeting the full production requirement. Any smaller prefix such as /27 would be insufficient.
A /27 subnet provides only 30 usable host addresses, which is less than the required 48 hosts and therefore cannot support the full production environment.
A /28 subnet provides only 14 usable host addresses, far fewer than the 48 required.
Concept tested: CIDR subnet sizing for host capacity
Source: https://datatracker.ietf.org/doc/html/rfc4632
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