This 200-301 practice question tests your understanding of network infrastructure and connectivity. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. A key principle to apply: subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which prefix length corresponds to the subnet mask 255.255.255.192?
/25
Why wrong: This is wrong because /25 corresponds to 255.255.255.128.
/26
This is correct because 255.255.255.192 equals 26 network bits.
/27
Why wrong: This is wrong because /27 corresponds to 255.255.255.224.
/28
Why wrong: This is wrong because /28 corresponds to 255.255.255.240.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
/26
The mask 255.255.255.192 corresponds to /26. In practical terms, the first three octets contribute 24 network bits, and 192 in binary is 11000000, which contributes 2 more network bits. That totals 26 network bits. This is a standard conversion skill that matters in subnetting, ACL design, and route interpretation.
Key principle: Subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
/25
Why it's wrong here
This is wrong because /25 corresponds to 255.255.255.128.
When this WOULD be correct
In a different question, if the exam asked for the prefix length of a subnet mask of 255.255.255.128, then option A: /25 would be the correct answer, as it accurately reflects that subnet mask.
/26
Why this is correct
This is correct because 255.255.255.192 equals 26 network bits.
Related concept
Subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host.
/27
Why it's wrong here
This is wrong because /27 corresponds to 255.255.255.224.
When this WOULD be correct
If the question asked for the prefix length for a subnet mask of 255.255.255.224, then option C: /27 would be the correct answer, as it accurately represents that subnet mask.
/28
Why it's wrong here
This is wrong because /28 corresponds to 255.255.255.240.
When this WOULD be correct
If the exam question asked for the prefix length corresponding to the subnet mask 255.255.255.240, then option D: /28 would be the correct answer, as it accurately represents that subnet mask.
Option-by-option analysis
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.
Why this is correct
This is correct because 255.255.255.192 equals 26 network bits.
Why this is wrong here
The /25 prefix length corresponds to subnet mask 255.255.255.128, not 255.255.255.192. The mask 255.255.255.128 has 128 in the last octet, while 255.255.255.192 has 192, indicating a different number of host bits.
★ When this WOULD be the correct answer
In a different question, if the exam asked for the prefix length of a subnet mask of 255.255.255.128, then option A: /25 would be the correct answer, as it accurately reflects that subnet mask.
Why candidates choose this
Students often confuse /25 and /26 because both are common subnet masks used for subnetting a /24 network. The difference of one bit can be overlooked, especially when quickly calculating subnet boundaries.
Why this is wrong here
The /27 prefix length corresponds to subnet mask 255.255.255.224, not 255.255.255.192. The mask 255.255.255.224 has 224 in the last octet, which provides 30 usable hosts per subnet, whereas 255.255.255.192 provides 62 usable hosts.
★ When this WOULD be the correct answer
If the question asked for the prefix length for a subnet mask of 255.255.255.224, then option C: /27 would be the correct answer, as it accurately represents that subnet mask.
Why candidates choose this
Students may mistakenly think that /27 is the next logical step after /26, but the actual progression is /25, /26, /27, /28. The value 192 in the mask can be misremembered as 224 due to similar numeric patterns.
Why this is wrong here
The /28 prefix length corresponds to subnet mask 255.255.255.240, not 255.255.255.192. The mask 255.255.255.240 has 240 in the last octet, which supports 14 usable hosts, while 255.255.255.192 supports 62 usable hosts.
★ When this WOULD be the correct answer
If the exam question asked for the prefix length corresponding to the subnet mask 255.255.255.240, then option D: /28 would be the correct answer, as it accurately represents that subnet mask.
Why candidates choose this
Students might confuse the decimal value 192 with 240 because both are common subnet mask values. Additionally, /28 is a frequently used prefix for small subnets, leading to a hasty association with any mask ending in a non-zero octet.
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?”
Common exam traps
Be careful not to confuse similar subnet masks or miscount the number of bits in the binary representation.
Detailed technical explanation
Subnetting is a fundamental networking concept that divides a larger IP network into smaller, manageable subnetworks. The subnet mask determines which portion of an IP address represents the network and which part represents the host. In IPv4, subnet masks are often expressed in dotted decimal notation or as prefix lengths (CIDR notation), where the prefix length indicates the number of bits set to 1 in the subnet mask. The subnet mask 255.255.255.192 translates to a binary mask of 11111111.11111111.11111111.11000000. This means the first 26 bits are network bits, and the remaining 6 bits are available for host addressing. Therefore, the prefix length is /26. Cisco devices and CCNA exam questions expect you to quickly convert between dotted decimal masks and prefix lengths to understand subnet boundaries, calculate host ranges, and configure routing or ACLs correctly. A common exam trap is confusing the subnet mask 255.255.255.192 with similar masks like 255.255.255.128 (/25) or 255.255.255.224 (/27). These masks differ by how many bits are allocated to the network portion, which directly affects the number of hosts per subnet. Misidentifying the prefix length can lead to incorrect subnetting, routing errors, or ACL misconfigurations in Cisco environments. Practically, understanding this conversion helps in designing efficient IP schemes and troubleshooting network segmentation.
Key takeaway
Subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host.
Real-world example
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Review subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — Subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host..
The correct answer is: /26 — The mask 255.255.255.192 corresponds to /26. In practical terms, the first three octets contribute 24 network bits, and 192 in binary is 11000000, which contributes 2 more network bits. That totals 26 network bits. This is a standard conversion skill that matters in subnetting, ACL design, and route interpretation.
Review subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host., then practise related 200-301 questions on the same topic to reinforce the concept.
Subnet masks define the boundary between network and host portions of an IP address by setting bits to 1 for network and 0 for host.
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Last reviewed: May 17, 2026
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