The answer is Azure Event Grid, the service that enables event-driven architectures by reacting to state changes in Azure resources. This is correct because Event Grid operates on a publish-subscribe model, where events from Azure services—such as a new blob being created in storage or a resource group being deleted—are instantly routed to subscribers like Azure Functions, Logic Apps, or webhooks, allowing automated reactions without polling. On the AZ-900 exam, this question tests your understanding of how Azure services handle real-time event processing, often appearing alongside questions about Azure Event Hubs (for streaming data) or Azure Service Bus (for messaging). A common trap is confusing Event Grid with Event Hubs; remember that Event Grid is for reacting to discrete state changes, not for ingesting high-volume telemetry. For a quick memory tip, think “Grid reacts to state changes” — the word “react” ties directly to Event Grid’s purpose of triggering actions when resources change.
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 service enables the creation of event-driven architectures by reacting to state changes in Azure resources?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Event Grid
Azure Event Grid is the correct service because it is a fully managed event routing service that enables event-driven architectures by reacting to state changes in Azure resources. It uses a publish-subscribe model where events from Azure services (e.g., blob storage, resource groups) are sent to subscribers like Azure Functions or webhooks, allowing automatic reactions to changes such as resource creation or deletion.
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.
✗
Azure Service Bus
Why it's wrong here
Service Bus provides reliable message queuing; Event Grid is for reactive event routing based on state changes.
✓
Azure Event Grid
Why this is correct
Event Grid routes events from Azure resource state changes to handlers like Functions and Logic Apps.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Event Hubs
Why it's wrong here
Event Hubs is for high-throughput streaming ingestion; Event Grid is for low-latency event routing.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse Azure Event Grid (event-driven reactions to state changes) with Azure Event Hubs (high-throughput data streaming) or Azure Service Bus (message queuing), because all three deal with events but serve fundamentally different purposes in Azure's messaging ecosystem.
Detailed technical explanation
How to think about this question
Azure Event Grid uses HTTP-based webhooks and supports multiple event schemas, including CloudEvents 1.0, to ensure interoperability. Under the hood, it guarantees at-least-once delivery and provides a latency of under 10 seconds for most events, making it suitable for real-time automation like auto-scaling VMs when a new blob is created. A real-world scenario is triggering an Azure Function to resize an image immediately after it is uploaded to Blob Storage.
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 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-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 Event Grid — Azure Event Grid is the correct service because it is a fully managed event routing service that enables event-driven architectures by reacting to state changes in Azure resources. It uses a publish-subscribe model where events from Azure services (e.g., blob storage, resource groups) are sent to subscribers like Azure Functions or webhooks, allowing automatic reactions to changes such as resource creation or deletion.
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.
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Question Discussion
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