- A
Use Azure Front Door, service endpoints, and Azure SQL Database with firewall rules.
Why wrong: Front Door is for global ingress; service endpoints are not as secure as Private Endpoints.
- B
Use Azure Application Gateway with WAF, network security groups (NSGs) on subnets, and Azure Private Endpoints for the database.
Application Gateway provides internet-facing WAF and path-based routing; NSGs restrict traffic between tiers; Private Endpoints keep database traffic private.
- C
Use Azure Load Balancer, Azure Firewall, and Azure SQL Database with public endpoint.
Why wrong: Load Balancer doesn't provide WAF; public database endpoint is not recommended.
- D
Use a single virtual network with three subnets, no NSGs, and Azure SQL Database with VNet injection.
Why wrong: No NSGs means no traffic enforcement between tiers.
AZ-305 Design infrastructure solutions Practice Question
This AZ-305 practice question tests your understanding of design infrastructure solutions. 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.
You need to design a virtual network architecture for a three-tier application in Azure. The web tier must be accessible from the internet, the application tier must only be accessible from the web tier, and the database tier must only be accessible from the application tier. Which combination of Azure services should you use?
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
Use Azure Application Gateway with WAF, network security groups (NSGs) on subnets, and Azure Private Endpoints for the database.
Option A is correct because it uses Azure Application Gateway for inbound internet traffic with WAF, NSGs to restrict traffic between tiers, and Private Endpoints for database access. Option B is wrong because Azure Load Balancer does not provide WAF or path-based routing. Option C is wrong because Azure Front Door is a global service, not for internal VNet traffic. Option D is wrong because placing all VMs in same subnet violates security.
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 Front Door, service endpoints, and Azure SQL Database with firewall rules.
Why it's wrong here
Front Door is for global ingress; service endpoints are not as secure as Private Endpoints.
- ✓
Use Azure Application Gateway with WAF, network security groups (NSGs) on subnets, and Azure Private Endpoints for the database.
- ✗
Use Azure Load Balancer, Azure Firewall, and Azure SQL Database with public endpoint.
Why it's wrong here
Load Balancer doesn't provide WAF; public database endpoint is not recommended.
- ✗
Use a single virtual network with three subnets, no NSGs, and Azure SQL Database with VNet injection.
Why it's wrong here
No NSGs means no traffic enforcement between tiers.
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 AZ-305 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this AZ-305 question test?
Design infrastructure solutions — This question tests Design infrastructure solutions — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Use Azure Application Gateway with WAF, network security groups (NSGs) on subnets, and Azure Private Endpoints for the database. — Option A is correct because it uses Azure Application Gateway for inbound internet traffic with WAF, NSGs to restrict traffic between tiers, and Private Endpoints for database access. Option B is wrong because Azure Load Balancer does not provide WAF or path-based routing. Option C is wrong because Azure Front Door is a global service, not for internal VNet traffic. Option D is wrong because placing all VMs in same subnet violates security.
What should I do if I get this AZ-305 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 AZ-305 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Last reviewed: Jun 20, 2026
This AZ-305 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 AZ-305 exam.
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