The correct answer is Azure Application Security Groups (ASGs) because they enable you to define network security policies based on logical application groups rather than static IP addresses. By assigning each tier’s virtual machines to its own ASG—such as WebASG, APIASG, and DBASG—you can create Network Security Group (NSG) rules that permit traffic only from WebASG to APIASG and from APIASG to DBASG, while explicitly blocking any direct WebASG-to-DBASG communication. On the AZ-305 exam, this scenario tests your understanding of micro-segmentation within a virtual network, often appearing as a distractor against options like Azure Firewall (overkill for intra-VNet control) or VNet peering (which connects separate VNets, not tiers). A common trap is assuming you need a firewall for all segmentation, but ASGs provide a simpler, cost-effective solution for multi-tier application security. Memory tip: think of ASGs as “logical labels” that let you write rules based on app roles, not IPs—just like assigning security badges to each tier.
AZ-305 Design infrastructure solutions Practice Question
This AZ-305 practice question tests your understanding of design infrastructure solutions. 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.
You are designing a network topology for a multi-tier application in Azure. The application has a web tier, an API tier, and a database tier. You need to ensure that the web tier can communicate with the API tier, and the API tier can communicate with the database tier, but the web tier cannot directly access the database tier. Which Azure networking solution should you implement?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Application Security Groups (ASGs)
Option B is correct because Azure Application Security Groups (ASGs) allow you to define network security policies based on application groups, and you can create rules that permit traffic only between specific tiers. Option A is wrong because NSGs alone would require complex rule management. Option C is wrong because Azure Firewall is a managed firewall but is overkill for this scenario. Option D is wrong because VNet peering is for connecting VNets, not controlling traffic within a VNet.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Azure Firewall
Why it's wrong here
Azure Firewall is a centralized firewall but is more expensive and complex than needed.
✗
Network Security Groups (NSGs) with service tags
Why it's wrong here
NSGs can filter traffic but managing rules for each tier can become complex.
✓
Azure Application Security Groups (ASGs)
Why this is correct
ASGs allow you to group VMs and define security rules based on application tiers, simplifying policy management.
Related concept
Standard ACLs match source addresses.
✗
VNet peering
Why it's wrong here
VNet peering connects separate VNets, not control traffic between subnets in the same VNet.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-305 question in full detail.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related AZ-305 ACL questions on filtering logic and placement.
Design infrastructure solutions — This question tests Design infrastructure solutions — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Azure Application Security Groups (ASGs) — Option B is correct because Azure Application Security Groups (ASGs) allow you to define network security policies based on application groups, and you can create rules that permit traffic only between specific tiers. Option A is wrong because NSGs alone would require complex rule management. Option C is wrong because Azure Firewall is a managed firewall but is overkill for this scenario. Option D is wrong because VNet peering is for connecting VNets, not controlling traffic within a VNet.
What should I do if I get this AZ-305 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related AZ-305 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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