AZ-204 Develop Azure compute solutions Practice Question
A team develops an Azure Functions app that processes IoT telemetry. They notice cold start latency is impacting performance. The function uses the Consumption plan. Which action reduces cold starts most effectively?
⚠ Common exam trap
Watch out — candidates often confuse the function timeout setting (which controls execution duration) with the cold start issue, or they think that Durable Functions inherently solve performance problems, when in fact they are for workflow orchestration and do not address cold starts.
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
✓
Change to Premium plan with pre-warmed instances
The Consumption plan for Azure Functions can cause cold start latency because the function app is deallocated after a period of inactivity. Changing to the Premium plan with pre-warmed instances keeps a specified number of instances always running and ready to handle requests, eliminating the cold start delay for those instances. This is the most effective action among the options to reduce cold starts.
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 Durable Functions for long-running workflows
Why it's wrong here
Durable Functions are designed for orchestrating stateful workflows, managing complex, long-running processes, and handling checkpoints or retries across multiple function executions. While they provide robust workflow management capabilities, they do not inherently reduce the cold start time for the underlying function app instances. The initial startup of the host environment and loading of the function code still occurs, potentially experiencing cold starts on consumption plans, even if orchestrated by Durable Functions.
- ✓
Change to Premium plan with pre-warmed instances
Why this is correct
The Azure Functions Premium plan is specifically engineered to eliminate cold starts by providing pre-warmed instances. This plan continuously keeps a specified number of instances active and ready to process requests, ensuring that new invocations do not incur the latency associated with starting up a new host or loading function code. It offers enhanced performance, VNet connectivity, and predictable scaling, making it ideal for latency-sensitive applications like IoT processing.
- ✗
Increase the function timeout to maximum
Why it's wrong here
Increasing the function timeout parameter only extends the maximum duration a single function execution is allowed to run before being terminated by the host. This setting directly impacts the execution time limit for a *running* function, not the initial startup time of the function app host or the loading of the function code. Therefore, adjusting the timeout has no effect on mitigating or reducing cold start latency.
- ✗
Use a dedicated App Service plan
Why it's wrong here
While hosting an Azure Functions app on a dedicated App Service plan (e.g., Basic, Standard, Premium V3) can indeed reduce cold starts by keeping instances always running, it is generally less optimized and potentially more expensive for serverless functions compared to the Azure Functions Premium plan. The Premium plan offers specific features tailored for functions, such as dynamic scaling with pre-warmed instances and VNet integration, often providing a better balance of performance and cost efficiency for event-driven workloads.
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 |
Go deeper
Related to this question
Learn chapter
Azure Functions Development
Key term
Durable Functions
Durable Functions is an extension of Azure Functions that lets you write stateful workflows in code, managing complex sequences of tasks, retries, and delays automatically.
Key term
Azure Functions Bindings
Azure Functions Bindings are declarative connections that link your serverless function code to Azure services or external resources, handling input and output data automatically without writing extra networking or authentication code.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.