Question 225 of 881
AZ-204 Develop Azure compute solutions Practice Question
You are designing a serverless data processing pipeline. The pipeline receives JSON messages from an Azure Event Hubs instance. Each message must be enriched with data from a Cosmos DB database and then written to a Parquet file in Azure Data Lake Storage Gen2. The enrichment step involves a lookup that takes approximately 2 seconds per message. The pipeline must process up to 1000 messages per second. You need to choose the most cost-effective and scalable compute option. Consider the following options: A) Use a single Azure Function with Event Hubs trigger and output to Data Lake Storage. B) Use a Durable Functions orchestration with fan-out/fan-in pattern. C) Use Azure Stream Analytics with a reference data input from Cosmos DB and output to Data Lake Storage. D) Use an Azure Databricks notebook with structured streaming. Which option should you recommend?
⚠ Common exam trap
It's easy for candidates to assume Azure Functions are the default serverless choice for all event processing, but they fail to recognize that per-message enrichment with a 2-second lookup creates a throughput bottleneck that only a streaming engine like Stream Analytics can handle cost-effectively at scale.
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 Stream Analytics with a reference data input from Cosmos DB and output to Data Lake Storage.
Azure Stream Analytics with a reference data input from Cosmos DB is the most cost-effective and scalable option because it can handle high-throughput streams (up to 1 GB/s) with sub-second latency, and it natively supports enriching incoming events with static or slowly-changing reference data (like Cosmos DB) without requiring custom code. The enrichment lookup is performed in-memory within the Stream Analytics job, avoiding per-message function invocation overhead and enabling linear scale-out across streaming units to meet 1000 messages/second with a 2-second lookup.
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 a single Azure Function with Event Hubs trigger and output to Data Lake Storage. [wrong]
Why it's wrong here
More expensive and complex for this use case.
- ✗
Use a Durable Functions orchestration with fan-out/fan-in pattern.
Why it's wrong here
Not designed for real-time stream processing; overhead.
- ✓
Use Azure Stream Analytics with a reference data input from Cosmos DB and output to Data Lake Storage.
Why this is correct
Scalable, serverless, supports enrichment and Parquet output.
- ✗
Use an Azure Databricks notebook with structured streaming. [wrong]
Why it's wrong here
Cannot handle high throughput with per-message delay.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 24, 2026
This AZ-204 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-204 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.