AZ-104 Implement and Manage Virtual Networking Practice Question
A team is creating a new workload subnet in a spoke virtual network. The subnet must support 41 VM NICs, 2 internal load balancer frontend IP configurations, 3 private endpoint IPs, and 4 spare IPs for near-term growth. Azure reserves 5 IP addresses in every subnet. What is the smallest IPv4 subnet size that satisfies the requirement?
⚠ Common exam trap
The trap here is that candidates often forget to include the 5 Azure-reserved IPs in their calculation, or they mistakenly think private endpoints or load balancer frontends do not consume subnet IPs, leading them to choose a smaller subnet like /27 or /28.
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, because 64 total addresses provide enough usable IPs for the workload and growth.
The total IP addresses required are 41 (VM NICs) + 2 (ILB frontends) + 3 (private endpoints) + 4 (spare) + 5 (Azure reserved) = 55 IPs. A /26 subnet provides 64 total addresses, of which 59 are usable (64 - 5 reserved), which meets the requirement. Option B is correct because /26 is the smallest subnet that provides enough usable IPs.
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, because 32 total addresses are enough for a small workload subnet.
Why it's wrong here
A /27 subnet contains 32 total addresses, but Azure reserves 5 of them (network, broadcast, and three infrastructure IPs), leaving only 27 usable host addresses. This is far below the requirement of 50 assignable IPs (41 VM NICs, 2 load balancer frontend IPs, 3 private endpoint IPs, and 4 for growth). Even if the workload were smaller, /27 cannot accommodate the stated minimum.
When this WOULD be correct
This option would be correct if the subnet needed to support only up to 27 IPs (e.g., 22 VM NICs, 2 ILB frontends, 1 private endpoint, and 2 spare IPs) and no additional growth beyond that.
- ✓
/26, because 64 total addresses provide enough usable IPs for the workload and growth.
Why this is correct
A /26 contains 64 total addresses. After Azure reserves 5, 59 remain usable, which covers 41 VM NICs, 2 load balancer frontend IPs, 3 private endpoint IPs, and 4 spare addresses. This is the smallest subnet size that meets the stated requirement without wasting a larger block than necessary.
- ✗
/25, because 128 total addresses are required once private endpoints are included.
Why it's wrong here
A /25 subnet does provide 128 total addresses and would meet the requirement, but it is not the smallest valid choice. After Azure's 5 reservations, it yields 123 usable IPs, which far exceeds the needed 50. Using a /25 wastes valuable IPv4 address space in the spoke virtual network and contradicts the principle of right-sizing subnets for current and near-term needs.
When this WOULD be correct
A question requiring support for a larger number of resources, such as 80 VM NICs, 5 load balancer frontends, 10 private endpoints, and 10 spare IPs, would need a /25 subnet (128 total addresses, 123 usable) to accommodate the total of 105 required IPs.
- ✗
/28, because 16 total addresses are sufficient when load balancers are used.
Why it's wrong here
A /28 subnet provides only 16 total addresses, and after Azure's 5 reserved addresses, just 11 usable IPs remain. Relying on load balancers does not reduce IP consumption; in fact, each load balancer frontend configuration consumes an IP from the subnet, and private endpoints also require dedicated addresses. This option drastically underestimates the total number of addresses needed.
When this WOULD be correct
This option would be correct if the question required a subnet for a small workload with only 6 VM NICs, 1 ILB frontend, 1 private endpoint, and 2 spare IPs, totaling 10 IPs, which fits within the 11 usable addresses of a /28.
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.
✓/26, because 64 total addresses provide enough usable IPs for the workload and growth.Correct answer▾
Why this is correct
A /26 contains 64 total addresses. After Azure reserves 5, 59 remain usable, which covers 41 VM NICs, 2 load balancer frontend IPs, 3 private endpoint IPs, and 4 spare addresses. This is the smallest subnet size that meets the stated requirement without wasting a larger block than necessary.
✗/27, because 32 total addresses are enough for a small workload subnet.Wrong answer — click to see why▾
Why this is wrong here
A /27 subnet provides only 32 total addresses, of which 5 are reserved by Azure, leaving 27 usable. The requirement is for 41 VM NICs, 2 ILB frontends, 3 private endpoints, and 4 spare IPs, totaling 50 IPs, which exceeds 27.
★ When this WOULD be the correct answer
This option would be correct if the subnet needed to support only up to 27 IPs (e.g., 22 VM NICs, 2 ILB frontends, 1 private endpoint, and 2 spare IPs) and no additional growth beyond that.
Why candidates choose this
Candidates may mistakenly think that the 5 reserved IPs are the only overhead and that 32 total addresses are enough for 41 IPs, or they may underestimate the total IP count by forgetting to include all resource types.
✗/25, because 128 total addresses are required once private endpoints are included.Wrong answer — click to see why▾
Why this is wrong here
A /25 subnet provides 128 total addresses, which is more than the required 41 VM NICs + 2 load balancer frontends + 3 private endpoints + 4 spare + 5 reserved = 55 IPs. The smallest subnet that meets the requirement is /26 (64 total addresses, 59 usable), so /25 is unnecessarily large and not the smallest.
★ When this WOULD be the correct answer
A question requiring support for a larger number of resources, such as 80 VM NICs, 5 load balancer frontends, 10 private endpoints, and 10 spare IPs, would need a /25 subnet (128 total addresses, 123 usable) to accommodate the total of 105 required IPs.
Why candidates choose this
Candidates may mistakenly think private endpoints or load balancers consume more IPs than they actually do, or they may overestimate growth requirements, leading them to choose a larger subnet than necessary.
✗/28, because 16 total addresses are sufficient when load balancers are used.Wrong answer — click to see why▾
Why this is wrong here
A /28 subnet provides only 16 total addresses, of which Azure reserves 5, leaving 11 usable. The requirement demands 41 VM NICs, 2 ILB frontends, 3 private endpoints, and 4 spare IPs, totaling 50 IPs, far exceeding 11 usable addresses.
★ When this WOULD be the correct answer
This option would be correct if the question required a subnet for a small workload with only 6 VM NICs, 1 ILB frontend, 1 private endpoint, and 2 spare IPs, totaling 10 IPs, which fits within the 11 usable addresses of a /28.
Why candidates choose this
Candidates may mistakenly think that Azure's 5 reserved IPs are included in the total, or they underestimate the number of required IPs, especially forgetting that private endpoints and load balancer frontends consume IPs from the subnet.
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?”
Visual reference
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Related to this question
Learn chapter
Managed Identities for Azure Resources
Key term
Private endpoint
A private endpoint is a network interface that securely connects a service over a private IP address inside a virtual network, keeping traffic off the public internet.
Key term
Load balancer
A load balancer is a device or software that distributes incoming network traffic across multiple servers so no single server gets overwhelmed.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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