CCNA Network Infrastructure and Connectivity Practice Question
A subnet must support at least 62 usable IPv4 host addresses. Which prefix is the most restrictive that meets the requirement?
⚠ Common exam trap
Avoid confusing total addresses with usable ones; remember to subtract network and broadcast addresses.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
/26
A /26 is the smallest valid answer. In practical terms, a /26 provides 64 total addresses and 62 usable host addresses after subtracting the network and broadcast addresses. A /27 would be too small because it provides only 30 usable hosts. This is a standard minimum-prefix question because it checks whether you can work backward from the host requirement and choose the smallest subnet that fits.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
/27
Why it's wrong here
This is wrong because /27 provides only 30 usable hosts.
When this WOULD be correct
If the question asked for the smallest subnet that supports at least 30 usable addresses, then /27 would be the correct answer, as it provides exactly 30 usable addresses.
- ✓
/26
Why this is correct
This is correct because /26 provides 62 usable host addresses.
- ✗
/25
Why it's wrong here
This is wrong because /25 works but is larger than necessary.
When this WOULD be correct
In a scenario where a question specifies the need for a subnet that can accommodate at least 126 usable addresses, option C: /25 would be the correct choice, as it meets the requirement without exceeding it unnecessarily.
- ✗
/24
Why it's wrong here
A /24 prefix provides 254 usable host addresses, which comfortably exceeds the requirement for at least 62 hosts. However, it is incorrect because the question specifies the *most restrictive* prefix. Selecting /24 allocates significantly more IP addresses than necessary, leading to inefficient use of address space. This option is tempting because /24 is a standard and frequently encountered subnet size for typical local area networks, often used when the exact host count is not a primary optimisation concern.
When this WOULD be correct
In a different scenario where the question asks for a subnet that can support a larger number of hosts, such as at least 200 usable addresses, /24 would be the correct answer as it provides 254 usable addresses.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓/26Correct answer▾
Why this is correct
This is correct because /26 provides 62 usable host addresses.
✗/27Wrong answer — click to see why▾
Why this is wrong here
A /27 subnet provides only 30 usable host addresses (32 total minus 2 for network and broadcast), which does not meet the requirement of at least 62 usable addresses.
★ When this WOULD be the correct answer
If the question asked for the smallest subnet that supports at least 30 usable addresses, then /27 would be the correct answer, as it provides exactly 30 usable addresses.
Why candidates choose this
Candidates may confuse the number of usable addresses with the total number of addresses in the subnet, leading them to mistakenly believe that /27 could meet a lower requirement than specified.
✗/25Wrong answer — click to see why▾
Why this is wrong here
Option C: /25 provides 126 usable host addresses, which exceeds the requirement of at least 62 usable addresses. However, it is not the smallest prefix that meets the requirement, as /26 suffices with 62 usable addresses.
★ When this WOULD be the correct answer
In a scenario where a question specifies the need for a subnet that can accommodate at least 126 usable addresses, option C: /25 would be the correct choice, as it meets the requirement without exceeding it unnecessarily.
Why candidates choose this
Candidates may choose option C because they recognize that /25 offers a substantial number of addresses, leading them to mistakenly believe it is the smallest prefix that meets the requirement without considering the specific need for minimality.
✗/24Wrong answer — click to see why▾
Why this is wrong here
Option D: /24 provides 256 total addresses, with 254 usable, which exceeds the requirement of at least 62 usable addresses. However, it is not the smallest prefix that meets the requirement.
★ When this WOULD be the correct answer
In a different scenario where the question asks for a subnet that can support a larger number of hosts, such as at least 200 usable addresses, /24 would be the correct answer as it provides 254 usable addresses.
Why candidates choose this
Candidates may choose /24 because it is a common subnet size that many are familiar with, leading them to assume it is a safe choice for any requirement without calculating the specific needs.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
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Related to this question
Learn chapter
IPv4 Addressing and Address Classes
Key term
IPv4
IPv4 is the fourth version of the Internet Protocol, a set of rules that assigns unique numerical addresses to devices so they can communicate over networks like the internet.
Key term
Usable hosts
Usable hosts are the IP addresses in a subnet that can actually be assigned to devices like computers, printers, or servers, excluding the network and broadcast addresses.
About these practice questions
This 200-301 question is part of Courseiva's 1,389-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.