DVA-C02 Development with AWS Services Practice Test 21 — 15 Questions

Question 1

A developer is deploying a web application using AWS Elastic Beanstalk. The application needs to store session state. The developer wants to ensure that session data is not lost if an EC2 instance is terminated. Which solution should the developer implement?

Accepted Answer

Store session data in an Amazon ElastiCache cluster.. Option D is correct because ElastiCache provides a managed, external cache for session state that persists independently of EC2 instances. Option A is wrong because instance store is ephemeral. Option B is wrong because EBS is tied to the instance and is lost on termination if not configured for persistence. Option C is wrong because S3 is not optimized for low-latency session storage.

Answer

Store session data in an Amazon EBS volume.

Answer

Store session data in an Amazon S3 bucket.

Answer

Store session data in the instance store.

Question 2

A company runs a microservices application on Amazon ECS with Fargate. The application consists of three services: frontend, orders, and payments. The frontend service is behind an Application Load Balancer (ALB). The orders service processes requests from frontend and sends messages to the payments service via an Amazon SQS queue. The payments service polls the queue. Recently, during peak hours, the orders service experiences high latency and the SQS queue depth increases significantly. The monitoring shows that the payments service is not keeping up. The company wants to scale the payments service based on the queue depth. The developer has configured an ECS Service Auto Scaling target tracking policy using the SQS queue's ApproximateNumberOfMessagesVisible metric. However, the payments service is not scaling up as expected. What is the most likely cause?

Accepted Answer

The target tracking policy is not configured correctly because ECS Service Auto Scaling requires a custom metric, and the metric may not have been published yet.. Option D is correct because the ECS Service Auto Scaling requires a custom metric to be published to CloudWatch, and it may take a few minutes for the metric to appear. Option A is wrong because Fargate tasks do not have a maximum task limit by default; the limit is per region and can be increased. Option B is wrong because the SQS ApproximateNumberOfMessagesVisible metric is available as a standard CloudWatch metric. Option C is wrong because the payments service polls the queue; the scaling policy should work regardless of polling frequency.

Answer

The SQS queue is not sending the ApproximateNumberOfMessagesVisible metric to CloudWatch.

Answer

The payments service has reached the maximum number of tasks allowed by the service quota.

Answer

The payments service is not configured to poll the SQS queue frequently enough.

Question 3

A company is using AWS CodePipeline to automate its CI/CD pipeline. The pipeline has a source stage that uses Amazon S3. The developer updates a file in the S3 bucket, but the pipeline does not start automatically. What is the MOST likely cause?

Accepted Answer

Amazon S3 versioning is not enabled on the bucket.. Option A is correct because S3 source actions require versioning enabled to detect changes. Option B is wrong because CloudTrail is not required. Option C is wrong because polling is not the default method. Option D is wrong because IAM permissions are separate from the detection mechanism.

Answer

The IAM role for CodePipeline does not have s3:GetObject permission.

Answer

The pipeline is configured to use polling instead of event-based triggers.

Answer

AWS CloudTrail is not enabled.

Question 4

A developer is building an application that processes user-uploaded images. The application uses Amazon S3 to store the images and AWS Lambda to generate thumbnails. When a user uploads an image to an S3 bucket, an S3 event notification triggers a Lambda function. The Lambda function processes the image and saves the thumbnail to another S3 bucket. The developer notices that sometimes the Lambda function is not triggered after an upload. The developer checks the Lambda function's CloudWatch logs and sees no invocation records for those uploads. The S3 bucket event notification configuration appears correct. What is the most likely cause of this issue?

Accepted Answer

The S3 bucket and the Lambda function are in different AWS regions.. Option A is correct because S3 event notifications might not be delivered if the bucket is in a different region than the Lambda function; the Lambda function must be in the same region as the S3 bucket for S3 event notifications. Option B is wrong because the Lambda function's IAM role does not affect invocation; it affects execution. Option C is wrong because S3 event notifications are not asynchronous; they are delivered synchronously. Option D is wrong because the destination bucket's permissions are not relevant to the invocation trigger.

Answer

The destination S3 bucket does not have the correct bucket policy to allow the Lambda function to write thumbnails.

Answer

The S3 event notification is configured as an asynchronous invocation, and the event is lost.

Answer

The Lambda function's execution role does not have permission to read from the S3 bucket.

Question 5

A company is running a containerized application on Amazon ECS with Fargate launch type. The application needs to access an Amazon S3 bucket. The company wants to follow the principle of least privilege. How should the developer provide the necessary permissions?

Accepted Answer

Create an IAM task role with S3 permissions and associate it with the ECS task definition.. Option B is correct because an IAM task role is the recommended way to grant permissions to ECS tasks. Option A is wrong because instance roles are for EC2, not Fargate. Option C is wrong because storing credentials in the container is insecure. Option D is wrong because EFS is for file storage, not for granting S3 permissions.

Answer

Use Amazon EFS to store access keys.

Answer

Assign an IAM instance profile to the Fargate tasks.

Answer

Store AWS credentials in the container image.

Question 6

A developer is using Amazon DynamoDB as the data store for a serverless application. The application experiences high read traffic, and the developer wants to reduce latency. The data is not frequently updated. Which DynamoDB feature should the developer use?

Accepted Answer

DynamoDB Accelerator (DAX). Option A is correct because DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency. Option B is wrong because Global Tables are for multi-region replication, not caching. Option C is wrong because TTL is for data expiration. Option D is wrong because auto scaling adjusts throughput, not latency.

Answer

DynamoDB Auto Scaling

Answer

DynamoDB Global Tables

Answer

DynamoDB Time to Live (TTL)

Question 7

A company is using AWS CodePipeline to automate the deployment of a web application. The pipeline has three stages: Source (Amazon S3), Build (AWS CodeBuild), and Deploy (AWS CodeDeploy). The application is deployed to an Auto Scaling group of EC2 instances. Recently, a deployment failed because the CodeDeploy agent on one of the instances was not running. The developer wants to ensure that the CodeDeploy agent is always running on all instances. What is the MOST efficient solution?

Accepted Answer

Modify the Auto Scaling group's launch configuration to include a user data script that installs and starts the CodeDeploy agent.. Option B is correct because using an EC2 user data script to install and start the CodeDeploy agent ensures it runs on instance launch. Option A is wrong because manual restart is not efficient. Option C is wrong because CloudWatch does not restart agents; it can only monitor. Option D is wrong because Systems Manager Run Command can fix the issue after detection, but user data is proactive.

Answer

Use AWS CloudTrail to monitor the CodeDeploy agent status and trigger an AWS Lambda function to restart it.

Answer

Configure a CloudWatch alarm to detect when the CodeDeploy agent is not running and restart it automatically.

Answer

Use AWS Systems Manager Run Command to run a script that checks and restarts the CodeDeploy agent on a schedule.

Question 8

A developer is creating an AWS Lambda function that processes files uploaded to an S3 bucket. The developer wants to invoke the Lambda function automatically when a new file is uploaded. Which approach should the developer use?

Accepted Answer

Configure S3 event notifications to invoke the Lambda function directly.. Option C is correct because S3 can send event notifications to Lambda directly. Option A is wrong because SQS is an intermediate step that adds complexity. Option B is wrong because CloudWatch Events is not the native way to trigger Lambda from S3. Option D is wrong because API Gateway is for HTTP APIs, not for S3 events.

Answer

Use Amazon API Gateway to expose an endpoint and have S3 call it.

Answer

Configure S3 to send events to an SQS queue, and configure Lambda to poll the queue.

Answer

Use Amazon CloudWatch Events to trigger Lambda on S3 PUT events.

Question 9

A developer is working on a serverless application that uses Amazon DynamoDB as the database. The application reads and writes data to a DynamoDB table named 'Orders'. The table has a partition key 'OrderID' and a sort key 'OrderDate'. The application experiences high read latency during peak hours. The developer checks the CloudWatch metrics and notices high ReadThrottleEvents for the table. The table's read capacity is set to on-demand mode. The developer also notices that the application performs many queries that scan the entire table to find orders by customer ID, which is not a key attribute. What should the developer do to reduce read throttling?

Accepted Answer

Create a Global Secondary Index (GSI) on the CustomerID attribute and query the index instead of scanning the table.. Option C is correct because creating a Global Secondary Index (GSI) on CustomerID allows efficient queries without scanning. Option A is wrong because increasing read capacity units doesn't apply to on-demand mode. Option B is wrong because on-demand mode already handles spikes, but throttling can still occur if a partition's throughput is exceeded. Option D is wrong because DAX is an in-memory cache that can reduce read load, but it doesn't fix the inefficient query pattern.

Answer

Enable DynamoDB Accelerator (DAX) to cache the read results.

Answer

Switch the table to provisioned capacity mode and increase the read capacity units.

Answer

Keep the table in on-demand mode but increase the maximum read capacity limit.

Question 10

A company is using AWS CloudFormation to deploy infrastructure. The developer wants to create a custom resource that runs a Lambda function during stack creation and update. What must the developer do to ensure the custom resource works correctly?

Accepted Answer

The Lambda function must send a response to an S3 pre-signed URL.. Option D is correct because the Lambda function must send a response to the pre-signed S3 URL to signal completion. Option A is wrong because the function does not need to return a value directly. Option B is wrong because the function can be in any language. Option C is wrong because the function can be in the same template or referenced by ARN.

Answer

The Lambda function must be defined in the same CloudFormation template.

Answer

The Lambda function must return a JSON object with the desired output.

Answer

The Lambda function must be written in Python.

Question 11

A company has a legacy application that generates log files on an EC2 instance. The developer needs to stream these log files to Amazon CloudWatch Logs in real time. The developer installed the CloudWatch agent on the EC2 instance and configured it to monitor the log files. However, the logs are not appearing in CloudWatch Logs. The developer checks the agent status and sees that the agent is running. What is the most likely cause of this issue?

Accepted Answer

The EC2 instance does not have an IAM role with the necessary CloudWatch Logs permissions.. Option A is correct because the CloudWatch agent needs an IAM role with permissions to put log events. Option B is wrong because the agent does not need internet access if using VPC endpoints. Option C is wrong because the agent configuration file does not require a log group to exist beforehand; it can create it. Option D is wrong because the agent can handle various log formats; format mismatch would not prevent logs from appearing, but they might be parsed incorrectly.

Answer

The log file format is not compatible with the CloudWatch agent.

Answer

The EC2 instance is in a private subnet without internet access.

Answer

The CloudWatch agent configuration file does not specify an existing log group.

Question 12

A developer is implementing a solution to store application logs from multiple EC2 instances. The logs must be stored in a centralized location for analysis. Which services can the developer use to achieve this? (Choose TWO.)

Accepted Answer

Amazon CloudWatch Logs. Option A is correct because CloudWatch Logs can aggregate logs from EC2 instances via the CloudWatch agent. Option C is correct because S3 can store log files as a centralized repository. Option B is wrong because CloudTrail is for API activity, not application logs. Option D is wrong because DynamoDB is not optimized for log storage. Option E is wrong because Kinesis Data Analytics processes streams, not stores logs.

Answer

AWS CloudTrail

Answer

Amazon Kinesis Data Analytics

Answer

Amazon DynamoDB

Question 13

A developer is using AWS Lambda to process records from an Amazon Kinesis Data Stream. The Lambda function is invoked with a batch of records. The function processes each record and then returns a response. The developer notices that some records are being processed multiple times. The function's execution time is within the Lambda timeout. The Kinesis stream has 10 shards. The developer wants to ensure that each record is processed exactly once. What should the developer do?

Accepted Answer

Modify the Lambda function to use the sequence number of each record to deduplicate processing.. Option B is correct because the Lambda function should use the sequence number to track processed records and avoid reprocessing. Option A is wrong because increasing batch size does not prevent duplicates. Option C is wrong because reducing concurrency can help but does not guarantee exactly-once processing. Option D is wrong because error handling does not address duplicate processing.

Answer

Reduce the number of shards to minimize the chance of duplicates.

Answer

Configure the Lambda function's error handling to retry only failed records.

Answer

Increase the batch size to process more records per invocation.

Question 14

A developer is designing a serverless application that processes streaming data from IoT devices. The application must be able to handle data from millions of devices and store the data in a durable, scalable data store. Which AWS services should the developer use? (Choose THREE.)

Accepted Answer

Amazon Kinesis Data Streams. Option A is correct because Kinesis Data Streams can ingest large volumes of streaming data. Option C is correct because Lambda can process the data in real-time. Option E is correct because DynamoDB is a scalable, durable data store suitable for IoT data. Option B is wrong because SQS is not a streaming service. Option D is wrong because RDS is not as scalable for high-throughput streaming data.

Answer

Amazon RDS

Answer

Amazon SQS

Question 15

A developer is building a serverless application using AWS Lambda to process images uploaded to an S3 bucket. The Lambda function needs to resize each image and store the result in another S3 bucket. Which TWO actions should the developer take to ensure the function can access the S3 buckets securely?

Accepted Answer

Create an IAM execution role for the Lambda function with permissions to read from the source bucket and write to the destination bucket.. Option A is correct because Lambda functions need an execution role with permissions. Option D is correct because S3 bucket policies can grant access to the Lambda function's execution role. Option B is incorrect because Lambda functions do not use IAM users. Option C is incorrect because EC2 instance profiles are for EC2, not Lambda. Option E is incorrect because Lambda does not use access keys directly.

Answer

Store the AWS access key and secret key in the Lambda environment variables.

Answer

Assign an IAM user to the Lambda function and embed the user's access key in the function code.

Answer

Attach an IAM instance profile to the Lambda function.