Azure Firewall is the correct choice because it delivers stateful, centralized network firewall capabilities with threat intelligence-based filtering, operating at layers 3 through 7 to inspect and block malicious traffic in real time. Unlike Network Security Groups, which are distributed and only provide basic stateful filtering at the subnet or NIC level, Azure Firewall uses a central policy to enforce consistent rules across your entire virtual network, and it integrates directly with Microsoft Threat Intelligence to automatically block known malicious IPs and domains. On the AZ-900 exam, this question tests your ability to distinguish between Azure’s network security services—specifically, Azure Firewall versus NSGs and Azure DDoS Protection—so remember that “stateful + centralized + threat intelligence” always points to Azure Firewall. A common trap is confusing NSGs as stateful at the network layer, but they lack the centralized policy and threat intelligence feed that Azure Firewall provides. Memory tip: think “Firewall = Full inspection, Intelligence, and Central control” to recall its three defining features.
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. 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.
Which Azure network security service provides stateful, centralized network firewall capabilities with threat intelligence-based filtering?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Firewall
Azure Firewall is the correct answer because it is a stateful, managed, cloud-based network security service that provides centralized network firewall capabilities with built-in threat intelligence-based filtering. Unlike Network Security Groups (NSGs), which are distributed and stateless or stateful at the subnet/NIC level, Azure Firewall inspects and filters traffic at the network and application layers (L3-L7) using a central policy, and it integrates with Microsoft Threat Intelligence to block known malicious IPs and domains in real time.
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.
✗
Network Security Groups
Why it's wrong here
NSGs provide basic stateless packet filtering at the subnet/NIC level — Azure Firewall is a full stateful firewall with advanced features.
✓
Azure Firewall
Why this is correct
Azure Firewall is a managed stateful network firewall with threat intelligence filtering, FQDN rules, and centralized management.
Related concept
Read the scenario before looking for a memorised answer.
Application Gateway WAF protects web applications at layer 7 — Azure Firewall provides broader network-level stateful filtering.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Network Security Groups (NSGs) with Azure Firewall because both filter traffic, but NSGs lack centralized management, application-layer inspection, and built-in threat intelligence, making Azure Firewall the only correct choice for a stateful, centralized firewall with threat intelligence-based filtering.
Detailed technical explanation
How to think about this question
Azure Firewall uses a static public IP address for outbound SNAT and inbound DNAT, and it supports FQDN-based filtering for outbound traffic, which NSGs cannot do natively. Under the hood, it leverages a highly available, auto-scaling infrastructure that inspects packets up to Layer 7, and its threat intelligence feeds are updated from Microsoft's global threat database, blocking traffic from known malicious IPs and domains in near real-time. In a real-world scenario, an enterprise with multiple virtual networks can route all internet-bound traffic through Azure Firewall using forced tunneling, ensuring centralized logging and policy enforcement across the entire Azure footprint.
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
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure Firewall — Azure Firewall is the correct answer because it is a stateful, managed, cloud-based network security service that provides centralized network firewall capabilities with built-in threat intelligence-based filtering. Unlike Network Security Groups (NSGs), which are distributed and stateless or stateful at the subnet/NIC level, Azure Firewall inspects and filters traffic at the network and application layers (L3-L7) using a central policy, and it integrates with Microsoft Threat Intelligence to block known malicious IPs and domains in real time.
What should I do if I get this AZ-900 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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Variation 1. Which Azure security service provides a cloud-native firewall with built-in high availability and unrestricted cloud scalability?
medium
A.Network Security Groups
B.Azure WAF
✓ C.Azure Firewall
D.Azure DDoS Protection
Why C: Azure Firewall is a cloud-native, stateful firewall as a service that provides built-in high availability and scales automatically to accommodate changing network traffic patterns. Unlike other options, it is designed specifically as a managed firewall service with unrestricted cloud scalability, supporting both inbound and outbound traffic filtering at the network and application layers.
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Question Discussion
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