Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A subnet must support at least 62 usable IPv4 host addresses. 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 /27 provides only 30 usable hosts.
B
Best answer
/26
This is correct because /26 provides 62 usable host addresses.
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 needed.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting a /27 prefix because it might seem close to the required host count, but it only provides 30 usable hosts, which is less than the needed 62. Another trap is choosing a /25 or /24 prefix, which do meet the host requirement but are unnecessarily large, wasting valuable IP address space. Candidates often confuse total addresses with usable hosts and forget to subtract the network and broadcast addresses, leading to incorrect subnet size choices. Understanding the exact host calculation and subnet mask implications is essential to avoid these mistakes.
Technical deep dive
How to think about this question
Subnetting is a fundamental concept in IPv4 networking that divides a larger network into smaller, manageable segments called subnets. 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 address. 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 subnet prefix that supports at least 62 usable hosts, you start by calculating the required host bits. Since 2^6 = 64 and subtracting 2 gives 62 usable hosts, a subnet with 6 host bits is needed. This corresponds to a /26 prefix (32 - 6 = 26). A /27 prefix provides only 5 host bits, yielding 30 usable hosts, which is insufficient. Larger prefixes like /25 or /24 provide more hosts than required but are not the smallest possible. A common exam trap is selecting a larger subnet prefix such as /25 or /24 because they meet the host requirement but are unnecessarily large, which wastes IP address space. Another trap is choosing /27, mistakenly thinking 32 total addresses provide 62 hosts. Understanding how to calculate usable hosts and the impact of network and broadcast addresses is critical. In practical Cisco networking, using the smallest subnet that meets requirements conserves IP addresses and optimizes routing efficiency.
KKey Concepts to Remember
- Subnetting divides an IPv4 network into smaller segments by allocating bits between 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 the network and broadcast addresses.
- A /26 prefix provides 64 total addresses and 62 usable host addresses, making it the smallest subnet to support at least 62 hosts.
- A /27 prefix provides only 32 total addresses and 30 usable hosts, which is insufficient for a subnet requiring 62 hosts.
- Choosing a subnet prefix larger than necessary, such as /25 or /24, wastes IP address space and reduces network efficiency.
- Cisco devices use subnet masks to determine network boundaries and route traffic appropriately within and between subnets.
- Understanding subnetting calculations helps avoid common exam traps related to host count and subnet size requirements.
- Efficient subnetting conserves IP addresses and improves network scalability and management in Cisco environments.
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.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
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 IPv4 network into smaller segments by allocating bits between network and host portions using a subnet mask or prefix length.
What is the correct answer to this question?
The correct answer is: /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.
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.
Discussion
Loading comments…
Sign in to join the discussion.