- A
/27
Why wrong: A /27 provides only 27 usable IP addresses after Azure reservations, which is not enough for all required resources.
- B
/26
A /26 provides 64 total addresses, and Azure reserves five, leaving 59 usable addresses. That is enough for 48 VMs, two load balancer frontend IPs, and one Bastion host.
- C
/25
Why wrong: A /25 would work, but it is larger than necessary and wastes address space that could be used elsewhere.
- D
/28
Why wrong: A /28 is far too small for this design and cannot support the number of required private IP addresses.
Question 745 of 1,170
AZ-104 Implement and Manage Virtual Networking Practice Question
This AZ-104 practice question tests your understanding of implement and manage virtual networking. 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. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.
A team is creating a subnet for 48 small Linux VMs, two internal load balancer frontend IPs, and one Azure Bastion host. Azure reserves five IP addresses in every subnet. Which subnet prefix is the smallest that will still meet the requirement?
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
The correct answer is /26 because it provides 64 total IP addresses, of which Azure reserves 5, leaving 59 usable IPs. This is the smallest prefix that accommodates the 48 VMs, 2 load balancer frontend IPs, and 1 Bastion host (total 51 required IPs). A /27 would only yield 32 total IPs (27 usable), which is insufficient.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
A /27 provides only 27 usable IP addresses after Azure reservations, which is not enough for all required resources.
When this WOULD be correct
If the requirement were for 22 VMs, 2 load balancer IPs, and 1 Bastion (25 IPs total), a /27 subnet (27 usable IPs) would be the smallest that meets the need.
- ✓
/26
Why this is correct
A /26 provides 64 total addresses, and Azure reserves five, leaving 59 usable addresses. That is enough for 48 VMs, two load balancer frontend IPs, and one Bastion host.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
/25
Why it's wrong here
A /25 would work, but it is larger than necessary and wastes address space that could be used elsewhere.
When this WOULD be correct
This option would be correct if the requirement were for 100-120 resources (e.g., 100 VMs, 10 load balancers, 5 Bastions) that need a subnet with at least 115 usable IPs, making /25 the smallest sufficient prefix.
- ✗
/28
Why it's wrong here
A /28 is far too small for this design and cannot support the number of required private IP addresses.
When this WOULD be correct
If the requirement were for a smaller number of resources, such as 8 VMs, 1 load balancer frontend, and no Bastion, a /28 subnet would be the smallest that meets the need (8+1=9 usable IPs, /28 gives 11 usable after reservation).
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 AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓/26Correct answer▾
Why this is correct
A /26 provides 64 total addresses, and Azure reserves five, leaving 59 usable addresses. That is enough for 48 VMs, two load balancer frontend IPs, and one Bastion host.
✗/27Wrong answer — click to see why▾
Why this is wrong here
A /27 subnet provides 32 total IPs, minus 5 reserved = 27 usable. The requirement is 48 VMs + 2 load balancer IPs + 1 Bastion = 51 IPs, so /27 is insufficient.
★ When this WOULD be the correct answer
If the requirement were for 22 VMs, 2 load balancer IPs, and 1 Bastion (25 IPs total), a /27 subnet (27 usable IPs) would be the smallest that meets the need.
Why candidates choose this
Candidates may mistakenly think /27 offers enough IPs (32 total) without subtracting the 5 reserved addresses, or underestimate the total number of required IPs.
✗/25Wrong answer — click to see why▾
Why this is wrong here
A /25 subnet provides 126 usable IP addresses (128 total minus 5 reserved), which is far more than the 51 needed (48 VMs + 2 load balancers + 1 Bastion). The question asks for the smallest prefix that meets the requirement, so /25 is too large.
★ When this WOULD be the correct answer
This option would be correct if the requirement were for 100-120 resources (e.g., 100 VMs, 10 load balancers, 5 Bastions) that need a subnet with at least 115 usable IPs, making /25 the smallest sufficient prefix.
Why candidates choose this
Candidates may think a larger subnet is safer or misremember the reserved IP count, or they might incorrectly calculate usable IPs (e.g., forgetting Azure reserves 5 IPs) and assume /25 is the minimum for 50+ resources.
✗/28Wrong answer — click to see why▾
Why this is wrong here
A /28 subnet provides only 14 usable IP addresses (16 total minus 5 reserved), which is insufficient for 48 VMs, 2 load balancer frontends, and 1 Bastion host (total 51 IPs needed).
★ When this WOULD be the correct answer
If the requirement were for a smaller number of resources, such as 8 VMs, 1 load balancer frontend, and no Bastion, a /28 subnet would be the smallest that meets the need (8+1=9 usable IPs, /28 gives 11 usable after reservation).
Why candidates choose this
Candidates may mistakenly think /28 is sufficient because they forget to subtract the 5 reserved IPs or underestimate the total IPs needed (48 VMs + 2 LBs + 1 Bastion = 51).
Analysis generated from the official AZ-104blueprint 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
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often forget Azure reserves 5 IPs per subnet and incorrectly calculate usable IPs as 2^(32-prefix) - 2 (like on-premises), leading them to choose /27 (thinking 30 usable IPs are enough) or /28 (thinking 14 usable IPs are enough).
Detailed technical explanation
How to think about this question
Azure reserves the first four and the last IP address in every subnet (network, gateway, Azure DNS, Azure future use, and broadcast). The subnet size must be calculated using the formula 2^(32-prefix) - 5 for usable IPs. For /26, 2^(32-26) = 64, minus 5 = 59 usable IPs, which comfortably covers the 51 required. In real-world scenarios, always account for Azure reserved IPs and any future scaling needs when choosing subnet sizes.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Visual reference
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FAQ
Questions learners often ask
What does this AZ-104 question test?
Implement and Manage Virtual Networking — This question tests Implement and Manage Virtual Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: /26 — The correct answer is /26 because it provides 64 total IP addresses, of which Azure reserves 5, leaving 59 usable IPs. This is the smallest prefix that accommodates the 48 VMs, 2 load balancer frontend IPs, and 1 Bastion host (total 51 required IPs). A /27 would only yield 32 total IPs (27 usable), which is insufficient.
What should I do if I get this AZ-104 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
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