AZ-204 Develop Azure compute solutions Practice Test 3 — 15 Questions

Question 1

You are developing a serverless application using Azure Functions. The application processes orders from a queue and writes results to Azure Cosmos DB. You need to ensure that the function scales out automatically to handle sudden spikes in order volume. Which two actions should you take? (Choose two.)

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Configure the function app to use the Premium plan with Always Ready instances enabled.. Option A is correct because the Premium plan supports rapid, event-driven scale-out with Always Ready instances that eliminate cold starts and allow the function app to instantly handle sudden spikes in queue-triggered order volume. Option E is correct because deploying to an App Service plan with multiple pre-allocated instances provides dedicated, already-running compute capacity that can absorb traffic bursts without waiting for scale-out provisioning. Options B, C, and D do not belong: the Consumption plan's max instance count setting only caps scaling rather than ensuring fast spike handling, a retry policy addresses throttling failures instead of scaling, and WEBSITE_MAX_DYNAMIC_APPLICATION_SCALE_OUT is a legacy setting that limits dynamic scale-out rather than enabling it.

Answer

Use the Consumption plan with a max instance count of 200.

Answer

Implement a retry policy in the queue trigger to handle throttling.

Answer

Set the function's WEBSITE_MAX_DYNAMIC_APPLICATION_SCALE_OUT app setting to 500.

Question 2

You are designing a serverless architecture using Azure Functions for a data processing pipeline. The pipeline must process messages from an Azure Service Bus queue. Each message can take up to 5 minutes to process. You need to ensure that if a function fails, the message is not lost and is retried after a delay. What should you configure?

Accepted Answer

Configure the Service Bus queue to dead-letter messages after a specified number of delivery attempts.. The original explanation correctly describes the full mechanism involving PeekLock mode, LockDuration (set to at least 5 minutes), MaxDeliveryCount, and dead-lettering. However, option D itself only covers the dead-lettering aspect (implying MaxDeliveryCount) and does not explicitly include the necessary LockDuration configuration, which is a critical part of the solution for the specified requirements.

Answer

Use the PeekLock message receive mode and manually complete the message only after successful processing.

Answer

Use Durable Functions with a retry policy.

Answer

Set the Azure Functions retry policy in the host.json file.

Question 3

You are developing an Azure Functions app that processes orders. Each order must be processed exactly once. The function is triggered by an Azure Event Hubs event. You need to ensure that if the function fails during processing, the event is not lost and is retried. Which THREE actions should you take?

Accepted Answer

Configure a dead-letter queue for events that exceed retry attempts.. Option B is correct because configuring a dead-letter queue (DLQ) for events that exceed the maximum retry attempts ensures that poison events are preserved and can be inspected or reprocessed later, preventing permanent data loss. Option D is correct because implementing checkpointing only after successful processing guarantees that the Event Hubs consumer offset is committed only when the order has been fully handled, so a failure causes the event to be redelivered rather than skipped. Option E is correct because the default checkpoint store in Azure Storage (the AzureWebJobsStorage account, using blob containers for leases and checkpoints) is the standard, supported mechanism for persisting checkpoints in Azure Functions Event Hubs triggers, enabling reliable at-least-once delivery. Option A is not appropriate because increasing batch size only changes throughput and does not affect retry or exactly-once semantics. Option C is incorrect because disabling checkpointing would cause events to be reprocessed repeatedly or lost depending on the offset behavior, and it does not provide the required retry guarantee.

Answer

Increase the batch size to process more events per invocation.

Answer

Disable checkpointing to avoid overhead.

Question 4

You have an Azure App Service that runs a web API. The API is accessed by multiple client applications. You need to implement authentication and authorization using Microsoft Entra ID. The solution must allow client applications to obtain access tokens using the OAuth 2.0 client credentials flow. Which authentication setting should you configure in the App Service?

Accepted Answer

Use the built-in authentication module with Microsoft Entra ID as the identity provider.. Configuring the built-in authentication module in Azure App Service with Microsoft Entra ID as the identity provider allows the App Service to validate access tokens issued by Microsoft Entra ID. Client applications can use the OAuth 2.0 client credentials flow to obtain tokens from Microsoft Entra ID and then present them to the App Service. The built-in auth module does not perform token acquisition; it only validates tokens at the gateway level, simplifying the validation process for the app.

Answer

Enable the 'Token store' in the Authentication / Authorization blade.

Answer

Configure the app to use the Microsoft.Identity.Web library to validate tokens.

Answer

Upload a client certificate and configure certificate-based authentication.

Question 5

You are building an Azure Functions app that processes messages from an Azure Service Bus queue. The function must process each message exactly once, and if processing fails, the message should be retried after a delay. You configure the function with a Service Bus trigger and set maxAutoRenewDuration to 5 minutes. During testing, you notice that messages are being processed multiple times even when processing succeeds. What is the most likely cause?

Accepted Answer

The function is using the default PeekLock mode, and the lock expires before the function completes.. The duplicate processing occurs because the message lock expires before the function completes. In PeekLock mode, the default lock duration is 1 minute. If the function takes longer, the lock is released and the message becomes visible again, allowing another instance to process it. Setting maxAutoRenewDuration to 5 minutes should automatically renew the lock, but if the function still exceeds that duration or if auto-renewal fails, duplicates can occur. The correct approach is to ensure the lock duration is sufficient or handle idempotency.

Answer

The function is using ReceiveAndDelete mode, which does not guarantee exactly-once processing.

Answer

The function's host.json is configured with a batchSize greater than 1, causing multiple messages to be processed concurrently.

Answer

The Service Bus queue is configured with duplicate detection enabled, causing messages to be reprocessed.

Question 6

You are developing an Azure Functions app that processes messages from an Azure Service Bus queue. The function must process each message exactly once and must be resilient to transient failures. You configure the function to use a Service Bus trigger with peeking lock. During testing, you notice that some messages are processed more than once. What is the most likely cause?

Accepted Answer

The function is not calling 'CompleteAsync' on the message after successful processing.. In peeking lock mode, the function must explicitly settle the message by calling 'CompleteAsync' after successful processing. If it does not, the message lock expires, and the message becomes visible again, leading to duplicate processing. The other options do not directly cause the same message to be processed multiple times.

Answer

The Service Bus queue is configured with duplicate detection enabled.

Answer

The function's 'maxAutoRenewDuration' is set too low, causing the lock to expire before processing completes.

Answer

The function's 'maxConcurrentCalls' is set to a value greater than 1, causing multiple instances to process the same message.

Question 7

You are developing an Azure Functions app that runs in a premium plan. The function must access a secret stored in Azure Key Vault. You want to avoid storing credentials in code or configuration. You configure a system-assigned managed identity for the function app and grant it access to the Key Vault. Which code snippet should you use to retrieve the secret?

Accepted Answer

var secret = await new SecretClient(new Uri("https://myvault.vault.azure.net/"), new DefaultAzureCredential()).GetSecretAsync("mySecret");. Using 'DefaultAzureCredential' with 'SecretClient' allows the function to authenticate using the system-assigned managed identity in Azure, while also supporting local development via other credential sources. This avoids embedding secrets in code or configuration, aligning with security best practices.

Answer

var secret = await new SecretClient(new Uri("https://myvault.vault.azure.net/"), new AzureCliCredential()).GetSecretAsync("mySecret");

Answer

var secret = await new SecretClient(new Uri("https://myvault.vault.azure.net/"), new ManagedIdentityCredential()).GetSecretAsync("mySecret");

Answer

var secret = await new SecretClient(new Uri("https://myvault.vault.azure.net/"), new EnvironmentCredential()).GetSecretAsync("mySecret");

Question 8

You are developing an Azure Functions app that uses a timer trigger to run every 5 minutes. The function must run only during business hours (9 AM to 5 PM) on weekdays. You need to configure the timer trigger schedule. Which CRON expression should you use?

Accepted Answer

0 */5 9-17 * * 1-5. The correct CRON expression is '0 */5 9-17 * * 1-5', which runs every 5 minutes during the hours of 9 AM to 5 PM on Monday through Friday. This matches the business hours and weekday requirement. Azure Functions timer triggers use a six-field CRON format that includes seconds, so the expression must have six fields. The other options either run all day, include weekends, or use non-standard notation.

Answer

0 */5 9-17 * * *

Answer

0 0/5 9-17 * * 1-5

Answer

0 */5 * * * 1-5

Question 9

You are deploying a containerized application to Azure Container Instances (ACI) using an Azure Resource Manager (ARM) template. The container image is stored in a private Azure Container Registry (ACR). You need to ensure that ACI can pull the image securely. What should you include in the ARM template?

Accepted Answer

The ACR resource ID and a system-assigned managed identity with AcrPull role.. Assigning a system-assigned managed identity to the container group and granting it the AcrPull role on the ACR allows ACI to authenticate securely without credentials. This is the recommended approach for pulling images from a private ACR.

Answer

The ACR login server URL and a personal access token.

Answer

The ACR admin username and password in the 'imageRegistryCredentials' property.

Answer

The ACR admin user enabled and the password stored in Azure Key Vault, referenced in the template.

Question 10

You are developing an Azure Functions app that must be triggered when a new message is added to an Azure Storage queue. You need to ensure that the function processes messages in a batch of up to 10 messages at a time. Which configuration setting should you use?

Accepted Answer

Set the 'batchSize' property in the function.json file to 10.. The 'batchSize' property in the function.json file for a Storage queue trigger determines how many messages are retrieved and processed in a single invocation. Setting it to 10 ensures the function processes up to 10 messages at a time.

Answer

Set the 'newBatchThreshold' property in the host.json file to 10.

Answer

Set the 'maxConcurrentCalls' property in the host.json file to 10.

Answer

Set the 'maxDequeueCount' property in the host.json file to 10.

Question 11

You are developing a solution that uses Azure Durable Functions to orchestrate a workflow. The orchestration must call an external HTTP endpoint that may take several minutes to respond. You need to ensure that the orchestration does not time out and can handle the long-running operation. Which two actions should you perform? (Choose two.)

Accepted Answer

Use the 'WaitForExternalEvent' method to pause the orchestration until the external endpoint signals completion.. Implementing the HTTP call as an activity function with a longer 'functionTimeout' allows the call to complete without timing out. Alternatively, using 'WaitForExternalEvent' pauses the orchestration until the external endpoint signals completion, which is ideal for long-running operations. These two actions address the timeout concern.

Answer

Use the 'CreateTimer' method to implement a polling mechanism that checks the status of the external operation periodically.

Answer

Set the 'maxConcurrentActivityFunctions' in host.json to a low value to prevent overload.

Answer

Use the 'CallActivityWithRetryAsync' method to call the activity function that makes the HTTP request, and configure a retry policy.

Question 12

You are implementing an Azure Durable Functions application that processes orders. The function must call three external APIs (payment gateway, inventory system, and shipping calculator) in parallel, then aggregate the results once all three have completed. Which Durable Functions pattern should you use?

Accepted Answer

Fan-out/Fan-in. The Fan-out/Fan-in pattern is designed exactly for this scenario: it triggers multiple function tasks in parallel (fan-out) and then aggregates their results once all complete (fan-in). In Durable Functions, this is implemented using `CallActivityAsync` in a loop with `Task.WhenAll` to wait for all parallel activities to finish, allowing the orchestrator to collect and process the combined results.

Answer

Function chaining

Answer

Monitor

Answer

Human interaction

Question 13

A company uses Azure Functions with a consumption plan. The function processes messages from a queue. During peak hours, the function takes longer to execute, and some messages are processed twice. What is the most likely cause?

Accepted Answer

The queue message visibility timeout is shorter than the function processing time.. In Azure Functions with a consumption plan, the queue message visibility timeout determines how long a message is invisible to other consumers after being dequeued. If the function's processing time exceeds this visibility timeout, the message becomes visible again and can be picked up by another function instance, leading to duplicate processing. This is the most likely cause of messages being processed twice during peak hours when execution times increase.

Answer

The function timeout is set too low.

Answer

The function uses blob output binding incorrectly.

Answer

The function app is using a premium plan instead of consumption.

Question 14

You are deploying a Node.js application to Azure Web Apps for Containers. The application needs to read configuration settings from Azure App Configuration. What is the recommended method to securely connect the app to the configuration store?

Accepted Answer

Use managed identity.. Using a managed identity allows the Node.js application running in Azure Web Apps for Containers to authenticate to Azure App Configuration without storing any secrets. Managed identities provide an automatically managed service principal in Microsoft Entra ID, enabling secure, code-free access to the configuration store via Microsoft Entra ID authentication, which is the recommended approach for production workloads.

Answer

Store connection string in environment variables.

Answer

Use Key Vault references in App Settings.

Answer

Hardcode the connection string.

Question 15

You are implementing an order processing system using Azure Durable Functions. The function must send notifications to multiple channels (email, SMS, push) in parallel and wait for all to complete before sending a confirmation. Which Durable Functions feature should you utilize?

Accepted Answer

Orchestration trigger with fan-out/fan-in pattern. The fan-out/fan-in pattern in Durable Functions allows you to invoke multiple activity functions in parallel (fan-out) and then wait for all of them to complete (fan-in) using `Task.WhenAll`. This is exactly what is needed to send notifications to email, SMS, and push simultaneously and then proceed only after all have finished, making option A correct.

Answer

Entity trigger

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Activity trigger with retry policy

Answer

Timer trigger