- A
Use Azure Bastion for management and VNet peering between web and database subnets.
Why wrong: VNet peering alone does not enforce traffic inspection or restrict internet exposure.
- B
Place web and database tiers in the same virtual network and use Network Security Groups (NSGs) to restrict access.
Why wrong: NSGs do not provide stateful inspection and cannot force traffic through a firewall.
- C
Use Azure Application Gateway to expose the web tier and place the database tier in a separate subnet with a deny-all NSG.
Why wrong: Application Gateway does not provide firewall functionality for outbound traffic from web to database.
- D
Deploy Azure Firewall in a hub virtual network and peer spoke virtual networks for each tier, routing traffic through the firewall.
Hub-spoke with Azure Firewall provides centralized security and forced tunneling.
Quick Answer
The answer is to deploy Azure Firewall in a hub virtual network and peer spoke virtual networks for each tier, routing all inter-tier traffic through the firewall. This hub-spoke network architecture with Azure Firewall is correct because it provides centralized, stateful inspection and forced tunneling, ensuring the database tier is isolated from the internet while the web tier remains publicly accessible only through the firewall’s rules. On the Microsoft Cybersecurity Architect exam, this scenario tests your understanding of how to achieve multi-tier application isolation with minimal internet exposure—a common trap is choosing Network Security Groups alone, which lack application-layer inspection, or relying on Application Gateway, which cannot restrict database access. The key memory tip is “Hub for control, spokes for isolation, firewall for inspection”—remember that only a centralized firewall enforces the required east-west traffic filtering between tiers.
SC-100 Design security solutions for infrastructure Practice Question
This SC-100 practice question tests your understanding of design security solutions for infrastructure. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company is planning to deploy a multi-tier application in Azure. The web tier must be accessible from the internet, while the database tier must be accessible only from the web tier and management jump boxes. The solution should minimize exposure to the internet. Which Azure architecture should you recommend?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
Deploy Azure Firewall in a hub virtual network and peer spoke virtual networks for each tier, routing traffic through the firewall.
Azure Firewall in a hub virtual network with forced tunneling through a firewall provides centralized control and minimizes exposure. NSGs cannot inspect traffic, and Application Gateway alone does not restrict database access. VNet peering without firewall does not enforce inspection.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Azure Bastion for management and VNet peering between web and database subnets.
Why it's wrong here
VNet peering alone does not enforce traffic inspection or restrict internet exposure.
- ✗
Place web and database tiers in the same virtual network and use Network Security Groups (NSGs) to restrict access.
Why it's wrong here
NSGs do not provide stateful inspection and cannot force traffic through a firewall.
- ✗
Use Azure Application Gateway to expose the web tier and place the database tier in a separate subnet with a deny-all NSG.
- ✓
Deploy Azure Firewall in a hub virtual network and peer spoke virtual networks for each tier, routing traffic through the firewall.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SC-100 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this SC-100 question test?
Design security solutions for infrastructure — This question tests Design security solutions for infrastructure — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Deploy Azure Firewall in a hub virtual network and peer spoke virtual networks for each tier, routing traffic through the firewall. — Azure Firewall in a hub virtual network with forced tunneling through a firewall provides centralized control and minimizes exposure. NSGs cannot inspect traffic, and Application Gateway alone does not restrict database access. VNet peering without firewall does not enforce inspection.
What should I do if I get this SC-100 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SC-100 subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
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Same concept, more angles
2 more ways this is tested on SC-100
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Your organization is planning to deploy a new web application on Azure VMs. The security team requires that all incoming traffic to the VMs be inspected by a network virtual appliance (NVA) before reaching the VMs. Which Azure networking solution should you use to route traffic through the NVA?
easy- A.Azure Firewall
- B.Azure Load Balancer
- C.Network Security Groups (NSGs)
- ✓ D.User Defined Routes (UDRs)
Why D: Option B is correct because User Defined Routes (UDRs) allow you to override Azure's default routing to force traffic through an NVA. Option A is wrong because Azure Firewall is a managed firewall service, not a routing mechanism. Option C is wrong because Azure Load Balancer distributes traffic but does not enforce routing through an NVA. Option D is wrong because NSGs filter traffic but do not route it.
Variation 2. You are designing a network security solution for a multi-tier application hosted in Azure. The front-end web tier must be accessible from the internet, but the back-end database tier must only accept traffic from the front-end tier. Which Azure service should you use to enforce this restriction?
easy- A.Azure Firewall
- ✓ B.Network Security Groups (NSGs)
- C.Azure Bastion
- D.Application Gateway
Why B: Option A is correct because Network Security Groups (NSGs) can be used to filter traffic between subnets. By applying an NSG to the database subnet with a rule allowing inbound traffic only from the front-end subnet's IP range, you restrict access. Option B is wrong because Azure Firewall is a managed firewall service, but for simple subnet-level filtering, NSGs are more appropriate and cost-effective. Option C is wrong because Application Gateway is a layer 7 load balancer. Option D is wrong because Azure Bastion provides secure RDP/SSH access to VMs.
Last reviewed: Jun 21, 2026
This SC-100 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SC-100 exam.
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