Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A subnet must support at least 62 usable hosts. Which prefix is the smallest that meets the requirement?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
/27
This is wrong because a /27 provides only 30 usable host addresses.
B
Best answer
/26
This is correct because a /26 provides 64 total addresses and 62 usable hosts.
C
Distractor review
/25
This is wrong because /25 works but is larger than necessary.
D
Distractor review
/24
This is wrong because /24 is much larger than required.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking the total number of IP addresses in a subnet for the number of usable host addresses. Candidates often select a /27 prefix because it provides 32 total addresses, mistakenly assuming it supports 62 hosts. However, two addresses are reserved for network and broadcast, leaving only 30 usable hosts, which is insufficient. Another trap is choosing a /25 prefix, which supports more than 62 hosts but wastes IP addresses unnecessarily. The key is to calculate usable hosts correctly and select the smallest prefix that meets the requirement without over-allocating.
Technical deep dive
How to think about this question
Subnetting is a fundamental concept in IP networking that divides a larger network into smaller, manageable subnetworks. Each subnet has a network address, a broadcast address, and a range of usable host addresses. The subnet mask or prefix length determines how many bits are allocated for the network portion versus the host portion of the IP address. In IPv4, the number of usable hosts in a subnet is calculated as 2^(number of host bits) minus 2, accounting for the network and broadcast addresses. To determine the smallest prefix that supports at least 62 usable hosts, you must find the subnet mask that provides at least 64 total addresses (62 usable plus 2 reserved). A /26 prefix corresponds to 255.255.255.192, which allocates 6 bits for hosts (2^6 = 64 addresses). This meets the requirement exactly, providing 62 usable host addresses. Prefixes longer than /26 (like /27) provide fewer hosts, while shorter prefixes (like /25 or /24) provide more hosts but waste address space. A common exam trap is confusing total addresses with usable hosts and selecting a prefix that either provides too few usable hosts or unnecessarily wastes IP addresses. For example, a /27 prefix offers 32 total addresses but only 30 usable hosts, which is insufficient. Conversely, a /25 prefix supports 126 usable hosts but is larger than needed, leading to inefficient IP address utilization. Understanding this distinction is critical for subnetting questions in the CCNA exam and practical network design.
KKey Concepts to Remember
- Subnetting divides an IP network into smaller subnets by allocating bits for network and host portions using a subnet mask or prefix length.
- The number of usable hosts in a subnet equals 2 raised to the number of host bits minus 2, accounting for network and broadcast addresses.
- A /26 prefix provides 64 total IP addresses, which results in 62 usable host addresses suitable for subnets requiring at least 62 hosts.
- Selecting a subnet prefix requires balancing between meeting host requirements and minimizing wasted IP addresses to optimize address utilization.
- A /27 prefix provides only 30 usable hosts, which is insufficient for a subnet needing at least 62 usable hosts.
- A /25 prefix supports 126 usable hosts but is larger than necessary when only 62 hosts are required, leading to inefficient IP allocation.
- Understanding the difference between total IP addresses and usable hosts is critical to correctly answering subnetting questions on the CCNA exam.
- Cisco devices and CCNA exam scenarios expect precise subnet calculations to ensure efficient network design and address management.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
Subnetting divides an IP network into smaller subnets by allocating bits for network and host portions using a subnet mask or prefix length.
What is the correct answer to this question?
The correct answer is: /26 — To support at least 62 usable hosts, the subnet needs 64 total addresses, because two of those will be reserved for the network and broadcast addresses. In plain language, the target is not 62 total addresses; it is 62 usable ones after the two reserved values are taken away. A /26 provides exactly 64 total addresses and therefore 62 usable host addresses. This is a classic minimum-prefix question because it checks whether you can convert a host requirement into the correct power-of-two subnet size without over-allocating unnecessarily. A /27 would be too small, while /25 would work but would waste more addresses than needed. The smallest valid prefix is /26.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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