DVA-C02 Development with AWS Services Practice Test 32 — 15 Questions

Question 1

A developer is designing a serverless application that processes large files uploaded to Amazon S3. Each file can be up to 5 GB. The processing involves extracting metadata and generating thumbnails. The developer wants to minimize processing time and cost. Which approach should the developer take?

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

Accepted Answer

Use an S3 event notification to invoke a Lambda function that downloads the file, processes it, and uploads results.. S3 event notifications can trigger a Lambda function immediately after an object is uploaded. The Lambda function can download the file from S3, extract metadata and generate thumbnails, then store the results. This approach is serverless and cost-effective, as you pay only for compute time. While Lambda has execution time and memory limits, processing a 5 GB file for metadata and thumbnails can be optimized to fit within these limits, making it the most appropriate choice among the options.

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Use S3 Object Lambda to process the object as it is being retrieved.

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Use an S3 event notification to invoke a Lambda function that copies the object to an EC2 instance for processing.

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Use AWS Fargate to run a container that polls S3 for new objects and processes them.

Question 2

A company uses Amazon CloudFront to distribute content from an S3 bucket. The content is static and rarely changes. The developer wants to reduce the load on the origin and improve performance for users. Which configuration change would achieve this?

Accepted Answer

Increase the TTL (Time to Live) for the cache behavior.. Increasing the TTL for the cache behavior tells CloudFront edge locations to retain cached copies of the static content for a longer period before re-validating with the origin S3 bucket. This reduces the number of requests that reach the origin, lowering load on the S3 bucket, and improves user performance by serving content directly from the edge cache more frequently.

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Disable caching for the distribution.

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Enable Lambda@Edge to process requests at edge locations.

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Decrease the TTL (Time to Live) for the cache behavior.

Question 3

A developer is using AWS Elastic Beanstalk to deploy a web application. The application experiences high latency during peak hours. The developer wants to scale the application automatically based on CPU utilization. Which configuration should the developer use?

Accepted Answer

Configure an Auto Scaling simple scaling policy based on Average CPU Utilization > 70% for scale-out and < 30% for scale-in.. AWS Elastic Beanstalk integrates with Auto Scaling to automatically adjust the number of EC2 instances based on a simple scaling policy that uses the Average CPU Utilization metric. By setting a scale-out threshold at >70% and a scale-in threshold at <30%, the application can dynamically handle peak-hour traffic while reducing costs during low usage. This directly addresses the developer's requirement to scale based on CPU utilization.

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Configure an Auto Scaling step scaling policy based on MemoryReservation metric.

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Use AWS CloudFront to cache responses and reduce load on the application.

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Configure an Auto Scaling target tracking policy based on NetworkIn metric.

Question 4

A developer needs to store application configuration data, such as database connection strings and third-party API keys, securely. The data must be encrypted at rest and automatically rotated. Which AWS service should the developer use?

Accepted Answer

AWS Secrets Manager. AWS Secrets Manager is the correct choice because it is specifically designed to securely store, encrypt, and automatically rotate secrets such as database connection strings and API keys. It integrates with AWS KMS for encryption at rest and provides built-in rotation capabilities for supported services like Amazon RDS, Redshift, and DocumentDB, meeting the requirement for automatic rotation without custom code.

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Amazon S3 with server-side encryption

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AWS Key Management Service (KMS)

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AWS Systems Manager Parameter Store

Question 5

A developer wants to invoke an AWS Lambda function every hour to perform a maintenance task. Which AWS service should be used to schedule the invocation?

Accepted Answer

Amazon CloudWatch Events (EventBridge). Amazon CloudWatch Events (now part of Amazon EventBridge) is the correct service for scheduling periodic invocations of AWS Lambda functions. It allows you to create a rule with a cron or rate expression (e.g., `rate(1 hour)`) that triggers the Lambda function on a defined schedule. This is the native, serverless way to run code on a recurring timer without managing any infrastructure.

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Amazon Simple Queue Service (SQS)

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AWS Step Functions

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Amazon Simple Notification Service (SNS)

Question 6

A developer is using Amazon S3 to host a static website. The website uses JavaScript to fetch data from an API Gateway endpoint. Users report that the website loads but API calls fail with HTTP 403 errors. The developer checks the S3 bucket policy and finds it allows public read access. What is the most likely cause?

Accepted Answer

The API Gateway API key is not included in the JavaScript code.. The website loads from S3, but the API calls to API Gateway fail with 403. This is often due to missing API key. If the API Gateway endpoint requires an API key and the JavaScript code does not include it in the request headers, API Gateway returns a 403 Forbidden error. Option C is correct because the most likely cause is that the API key is not included in the JavaScript code, leading to the 403 response.

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The S3 bucket policy blocks access from the API Gateway domain.

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The S3 bucket is not configured for static website hosting.

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The S3 bucket does not have CORS configuration to allow cross-origin requests from the API Gateway domain.

Question 7

A company is using AWS Lambda with a 1 GB memory configuration. The function processes large CSV files from S3 and occasionally times out after 15 seconds. The function currently uses synchronous invocation. What is the MOST cost-effective solution to handle larger files without losing data?

Accepted Answer

Increase the Lambda timeout to 15 minutes and keep memory at 1 GB.. Increasing the Lambda timeout from 15 seconds to 15 minutes directly addresses the timeout issue without incurring additional costs. Keeping memory at 1 GB avoids the higher per-GB-second cost of larger memory configurations, making it the most cost-effective solution. Lambda charges based on memory allocation and execution duration, so extending the timeout alone does not increase the cost per invocation if the function runs for the same duration.

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Switch to asynchronous Lambda invocation to allow up to 15 minutes of processing.

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Increase the Lambda memory to 3 GB to improve processing speed.

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Use AWS Step Functions to orchestrate the processing in smaller chunks.

Question 8

A developer is using AWS SAM to deploy a serverless application. The template includes a Lambda function that connects to an RDS MySQL database. The function works correctly in the developer's account but fails with a timeout when deployed to a production account. What is the MOST likely cause?

Accepted Answer

The Lambda function is not attached to the same VPC as the RDS instance.. The most likely cause is that the Lambda function is not attached to the same VPC as the RDS instance. Lambda functions run in a VPC by default only if explicitly configured; without VPC attachment, the function cannot reach the RDS database's private IP address, leading to a connection timeout. The developer's account may have had the RDS instance publicly accessible or the Lambda function was inadvertently in the same VPC, but the production account likely uses a private RDS instance in a VPC that the Lambda function is not connected to.

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The Lambda function timeout is set too low for the database query.

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The SAM template does not support RDS as an event source.

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The Lambda function uses a runtime that is not compatible with the MySQL client.

Question 9

A developer needs to securely store database credentials for a Lambda function. The credentials must be automatically rotated every 30 days. Which service should be used?

Accepted Answer

AWS Secrets Manager. AWS Secrets Manager is the correct choice because it is specifically designed to securely store, manage, and automatically rotate database credentials and other secrets. It supports built-in rotation with AWS Lambda, allowing you to set a rotation schedule (e.g., every 30 days) without custom infrastructure. This service integrates directly with Amazon RDS, Redshift, and DocumentDB for seamless credential rotation.

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AWS Key Management Service (KMS)

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AWS Systems Manager Parameter Store

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AWS CloudHSM

Question 10

A company is using Amazon CloudFront to distribute static content from an S3 bucket. The content is updated frequently, but users see stale content. The developer wants to ensure that new content is served as soon as possible after an update. Which action should be taken?

Accepted Answer

Create a CloudFront invalidation for the updated files.. CloudFront caches content at edge locations based on TTL settings. When content is updated in the S3 origin, existing cached copies remain stale until they expire or are explicitly invalidated. Creating a CloudFront invalidation for the updated files immediately removes the cached objects from all edge locations, forcing CloudFront to fetch the latest version from S3 on the next request. This ensures new content is served as soon as possible after an update.

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Enable 'Origin Shield' to reduce the number of requests to S3.

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Set the 'Minimum TTL' to 0 and 'Default TTL' to 0.

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Set the 'Object Caching' to 0 in the CloudFront distribution.

Question 11

A developer is building a real-time chat application using WebSocket APIs in API Gateway and Lambda. The application must handle thousands of concurrent connections. Which TWO actions should the developer take to ensure the application scales properly?

Accepted Answer

Set the Lambda function's reserved concurrency to a high enough value.. Setting reserved concurrency ensures the Lambda function has enough allocated capacity to handle the high volume of concurrent WebSocket connections without being throttled by the account-level concurrency limit. Without reserved concurrency, the function could experience throttling errors (HTTP 429) during traffic spikes, causing dropped connections and poor user experience.

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Use CloudFront to distribute the WebSocket endpoints.

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Place the Lambda function in a VPC to improve security.

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Enable API Gateway caching to reduce Lambda invocations.

Question 12

A developer wants to upload a large file (5 GB) to an Amazon S3 bucket using the AWS SDK. Which approach is MOST efficient and resilient?

Accepted Answer

Use the Multipart Upload API to upload the file in parts.. The Multipart Upload API is specifically designed for large objects (over 100 MB, recommended for 5 GB). It allows uploading a file in parallel parts, which improves throughput and resilience by enabling retries of individual failed parts without restarting the entire upload. This approach also supports pausing and resuming uploads, making it the most efficient and resilient method for a 5 GB file.

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Generate a presigned URL and use a third-party tool to upload.

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Invoke an AWS Lambda function to upload the file.

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Use the PutObject API call with the entire file.

Question 13

A developer is deploying a microservices architecture on Amazon ECS with Fargate. Each service needs to store sensitive configuration data such as database passwords. The developer wants to avoid hardcoding secrets in the application code. Which approach should the developer use?

Accepted Answer

Store the secrets in AWS Systems Manager Parameter Store or AWS Secrets Manager and reference them in the ECS task definition using the 'secrets' parameter.. AWS Systems Manager Parameter Store and AWS Secrets Manager are purpose-built services for securely storing and managing sensitive configuration data. By referencing secrets via the `secrets` parameter in the ECS task definition, the secrets are injected into the container at runtime without being exposed in the application code, task definition plaintext, or Docker image. This approach integrates natively with ECS Fargate and supports automatic rotation of secrets.

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Store the secrets in an Amazon S3 bucket and use a pre-signed URL to download them at startup.

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Define the secrets as environment variables in the ECS task definition.

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Encrypt the secrets using AWS KMS and store the encrypted blob in a configuration file within the Docker image.

Question 14

A developer needs to analyze real-time streaming data from thousands of devices. The data consists of JSON messages that must be processed and stored in Amazon S3. Which AWS service should the developer use to ingest and buffer the streaming data?

Accepted Answer

Amazon Kinesis Data Streams. Amazon Kinesis Data Streams is designed for real-time ingestion and buffering of large-scale streaming data, such as JSON messages from thousands of devices. It can capture and store data in shards for up to 365 days, allowing downstream consumers (e.g., Lambda, Kinesis Data Analytics) to process the data before storing it in Amazon S3. This makes it the correct choice for ingesting and buffering the streaming data before persistent storage.

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Amazon S3

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AWS Lambda

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Amazon Simple Queue Service (SQS)

Question 15

A developer is building an application that uses Amazon DynamoDB as a data store. The application reads the same item frequently but writes rarely. The developer wants to reduce read costs. Which DynamoDB feature should the developer use?

Accepted Answer

DynamoDB Accelerator (DAX). DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency from single-digit milliseconds to microseconds. Since the application reads the same item frequently but writes rarely, DAX can serve repeated read requests from its cache, significantly reducing the number of read capacity units consumed against the DynamoDB table and thus lowering read costs.

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DynamoDB Global Tables

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DynamoDB Auto Scaling

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Time to Live (TTL)