AZ-900 Describe Azure architecture and services Practice Question
Which Azure service provides a serverless event routing service that connects event sources to event handlers?
⚠ Common exam trap
A common mix-up: candidates confuse event routing (Event Grid) with message queuing (Service Bus) or data streaming (Event Hubs), but Event Grid is specifically designed for serverless, reactive event distribution without polling or managing queues.
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
✓
Azure Event Grid
Azure Event Grid is a fully managed serverless event routing service that uses a publish-subscribe model to connect event sources (e.g., Azure Blob Storage, resource groups) to event handlers (e.g., Azure Functions, webhooks). It filters and routes events based on event types and subscriptions, enabling reactive programming without polling or custom infrastructure.
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
Azure Service Bus is a fully managed enterprise message broker that supports queues, topics, and pub/sub with competing consumers, sessions, transactions, and duplicate detection. It is designed for reliable point-to-point or complex messaging workflows where workloads are processed at variable rates, not for low-latency event routing from Azure resources to serverless handlers. Event Grid, in contrast, is a reactive push-based router that filters and delivers discrete events to multiple subscribers, while Service Bus consumers typically pull messages and manage their own workflows.
- ✗
Azure Event Hubs
Why it's wrong here
Azure Event Hubs is a big data streaming platform and event ingestion service that receives millions of events per second and retains them in partitioned streams for replay by stream processors or analytics engines. It is built for telemetry and log ingestion with sequential, per-partition ordering, not for routing discrete state-change events to registered subscriber endpoints. Event Grid is a low-latency pub/sub routing fabric that pushes events to webhooks, Azure Functions, or other handlers, whereas Event Hubs consumers continuously poll or read from a partition and process the stream.
- ✓
Azure Event Grid
Why this is correct
Azure Event Grid is a highly scalable, fully managed event routing service that delivers discrete events from sources such as Blob Storage, resource groups, or custom applications to subscribers with near-real-time latency. It supports rich event filtering, fan-out to multiple handlers, automatic retry with dead-lettering, and built-in integration with Azure Functions, Logic Apps, and webhooks. This makes it the correct choice for reactive event-driven architectures where you need to trigger workflows automatically when an Azure resource changes state, typically without polling.
- ✗
Azure Queue Storage
Why it's wrong here
Azure Queue Storage is a simple, durable message queue service with REST-based APIs, commonly used to decouple application components and process backlogged work via worker roles or Azure Functions. It offers at-least-once delivery but lacks event schemas, pub/sub broadcast, filtering, and push-based multi-subscriber routing—messages must be polled from the queue by a single consumer. Event Grid, by contrast, broadcasts event notifications to many subscribers through a distributed subscription model, making Queue Storage unsuitable for this event-routing scenario.
Quick reference
Azure Blob Storage Tier Comparison
| Tier | Storage Cost | Retrieval Cost | Latency | Use Case |
|---|---|---|---|---|
| Hot | Highest | Lowest | Immediate | Active data, frequent reads |
| Cool | Lower | Higher | Immediate | Data accessed < once / month |
| Cold | Lower still | Higher | Immediate | Data accessed < once / quarter |
| Archive | Lowest | Highest + rehydration delay | Hours | Long-term compliance retention |
Go deeper
Related to this question
Learn chapter
Azure Regions and Geographies
Key term
Blob storage
Blob storage is a cloud service for storing large amounts of unstructured data, such as text or binary data, like documents, images, and videos.
Key term
Serverless
Serverless is a cloud computing model where the cloud provider manages the servers, and you only pay for the actual compute time your code uses, without having to worry about provisioning or maintaining infrastructure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-900 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-900 exam.