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: the subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet.. 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.
What prefix length corresponds to the subnet mask 255.255.255.224?
/26
Why wrong: This is wrong because /26 would correspond to 255.255.255.192.
/27
This is correct because 255.255.255.224 represents 27 network bits.
/28
Why wrong: This is wrong because /28 would correspond to 255.255.255.240.
/29
Why wrong: This is wrong because /29 would correspond to 255.255.255.248.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
/27
The subnet mask 255.255.255.224 corresponds to /27. In plain language, the first three octets contribute 24 network bits, and 224 in binary is 11100000, which contributes 3 more network bits. That gives a total of 27 network bits. This is a common prefix-conversion question because it checks whether you can move between dotted-decimal masks and prefix lengths confidently.
Key principle: The subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
/26
Why it's wrong here
This is wrong because /26 would correspond to 255.255.255.192.
When this WOULD be correct
In a different question asking for the prefix length of a subnet mask of 255.255.255.192, option A would be correct as it corresponds to a /26 prefix length. This would involve a scenario where the subnetting needs are for a larger subnet than /27.
/27
Why this is correct
This is correct because 255.255.255.224 represents 27 network bits.
Related concept
The subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet.
/28
Why it's wrong here
This is wrong because /28 would correspond to 255.255.255.240.
When this WOULD be correct
If the question asked for the prefix length corresponding to the subnet mask 255.255.255.240, then option C: /28 would be the correct answer, as it accurately reflects that specific subnet mask.
/29
Why it's wrong here
This is wrong because /29 would correspond to 255.255.255.248.
When this WOULD be correct
In a different exam scenario, if the question asked for the prefix length of a subnet mask of 255.255.255.248, then /29 would be the correct answer, as it provides 8 IP addresses with 6 usable ones.
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 255.255.255.224 represents 27 network bits.
Why this is wrong here
The /26 prefix corresponds to subnet mask 255.255.255.192, which has 64 addresses per subnet, not 32. The mask 255.255.255.224 has 27 network bits, not 26.
★ When this WOULD be the correct answer
In a different question asking for the prefix length of a subnet mask of 255.255.255.192, option A would be correct as it corresponds to a /26 prefix length. This would involve a scenario where the subnetting needs are for a larger subnet than /27.
Why candidates choose this
Students often confuse the number of bits borrowed; /26 is a common prefix and might be mistakenly associated with 224 because both are used in subnetting.
Why this is wrong here
The /28 prefix corresponds to subnet mask 255.255.255.240, which provides 16 addresses per subnet (14 usable). The mask 255.255.255.224 has 32 addresses per subnet, so /28 is incorrect.
★ When this WOULD be the correct answer
If the question asked for the prefix length corresponding to the subnet mask 255.255.255.240, then option C: /28 would be the correct answer, as it accurately reflects that specific subnet mask.
Why candidates choose this
Students may think that 224 in the last octet implies 28 bits because 224 is close to 240, or they might misremember the binary conversion.
Why this is wrong here
The /29 prefix corresponds to subnet mask 255.255.255.248, which provides 8 addresses per subnet (6 usable). The mask 255.255.255.224 has 32 addresses, so /29 is incorrect.
★ When this WOULD be the correct answer
In a different exam scenario, if the question asked for the prefix length of a subnet mask of 255.255.255.248, then /29 would be the correct answer, as it provides 8 IP addresses with 6 usable ones.
Why candidates choose this
Students might confuse the number of host bits; /29 is a common prefix for small subnets, and the 224 mask might be mistakenly associated with a higher prefix length due to its larger numeric value.
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 cautious not to confuse the binary values of different subnet masks. Always convert the last octet to binary to determine the correct prefix length.
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 refers to the network and which part refers to hosts. In IPv4, subnet masks are often expressed in dotted-decimal notation (e.g., 255.255.255.224) or as a prefix length (e.g., /27), indicating the number of bits used for the network portion. The subnet mask 255.255.255.224 corresponds to a prefix length of /27 because the first three octets (255.255.255) contribute 24 bits, and the fourth octet (224) in binary is 11100000, adding 3 more bits to the network portion. This totals 27 bits for the network and subnet combined, leaving 5 bits for host addressing. Cisco devices and CCNA exams require fluency in converting between these notations to understand network segmentation and address allocation. A common exam trap is confusing similar subnet masks with close prefix lengths, such as mistaking 255.255.255.224 (/27) for 255.255.255.192 (/26). This happens because the decimal values are close, but the binary representation differs significantly. Practically, using the correct prefix length ensures accurate subnetting, proper IP address allocation, and effective routing in Cisco networks, which is critical for network design and troubleshooting.
Key takeaway
The subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet.
Real-world example
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Review the subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet., 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 — The subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet..
The correct answer is: /27 — The subnet mask 255.255.255.224 corresponds to /27. In plain language, the first three octets contribute 24 network bits, and 224 in binary is 11100000, which contributes 3 more network bits. That gives a total of 27 network bits. This is a common prefix-conversion question because it checks whether you can move between dotted-decimal masks and prefix lengths confidently.
Review the subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet., then practise related 200-301 questions on the same topic to reinforce the concept.
The subnet mask 255.255.255.224 uses 27 bits for the network portion, combining 24 bits from the first three octets and 3 bits from the fourth octet.
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Last reviewed: Apr 12, 2026
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