DVA-C02 Development with AWS Services Practice Test 34 — 15 Questions

Question 1

A developer wants to store application configuration data that can be accessed by multiple microservices. The data is sensitive and should be encrypted at rest. Which AWS service should be used to meet these requirements?

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

Accepted Answer

AWS Systems Manager Parameter Store. AWS Systems Manager Parameter Store provides a secure, hierarchical store for configuration data and secrets. It supports encryption at rest using AWS KMS, integrates with AWS IAM for fine-grained access control, and is designed for use by multiple microservices via the AWS SDK or CLI. This makes it the ideal choice for storing sensitive application configuration that must be encrypted at rest and accessed by distributed services.

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Amazon S3

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AWS Identity and Access Management (IAM)

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Amazon DynamoDB

Question 2

A developer is using AWS CodePipeline to deploy a web application to an Auto Scaling group. The pipeline includes a deploy action that uses CodeDeploy. The deployment fails with the error: 'The overall deployment failed because too many individual instances failed deployment, too few healthy instances are available, or some instances in your deployment group are experiencing problems.' Which of the following is the MOST likely cause?

Accepted Answer

The deployment configuration has a minimum healthy instances setting that is too restrictive.. The error message indicates that the deployment failed because too many instances were unhealthy or failed. The most likely cause is that the deployment configuration's minimum healthy hosts setting is too restrictive, meaning it requires a higher percentage of healthy instances during deployment than the environment can sustain, causing CodeDeploy to stop the deployment when the threshold is breached.

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The CodeDeploy agent is not sending logs to CloudWatch.

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The application's lifecycle hooks are failing during the ApplicationStop event.

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The instances were launched from an AMI that does not have the CodeDeploy agent installed.

Question 3

A company uses Amazon API Gateway to expose a REST API backed by AWS Lambda. The API is experiencing high latency. The developer suspects cold starts are contributing to the latency. Which action would be MOST effective in reducing cold start latency?

Accepted Answer

Increase the memory allocation of the Lambda function.. Increasing the memory allocation of a Lambda function directly correlates to allocating more CPU power, which reduces the initialization time during a cold start. AWS Lambda provisions CPU proportionally to the configured memory, so a higher memory setting speeds up the runtime environment setup and code loading, thereby lowering cold start latency.

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Place the Lambda function in a VPC to improve network latency.

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Enable Lambda@Edge to cache responses.

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Increase the function timeout to 15 minutes.

Question 4

A developer needs to store session state data for a web application running on multiple EC2 instances. The data must be highly available and durable. Which AWS service should be used?

Accepted Answer

Amazon ElastiCache. Amazon ElastiCache is the correct choice because it provides a managed, in-memory caching service that is ideal for storing session state data with high availability and durability. By using ElastiCache for Redis or Memcached, session data is stored outside of individual EC2 instances, ensuring that if an instance fails, the session state is preserved and can be accessed by other instances in the application tier. ElastiCache supports replication and automatic failover, meeting the requirements for high availability and durability.

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Amazon S3

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Amazon EBS

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Amazon CloudFront

Question 5

A company uses AWS Lambda functions behind an API Gateway REST API. The Lambda functions are written in Python and use the boto3 SDK to interact with DynamoDB. After a recent deployment, some users report sporadic 502 Bad Gateway errors when calling the API. The Lambda function logs show occasional 'AccessDeniedException' errors. What is the most likely cause and solution?

Accepted Answer

The Lambda execution role lacks permissions to access DynamoDB. Update the role to include the necessary DynamoDB actions.. The 'AccessDeniedException' error in the Lambda logs indicates that the Lambda function's execution role does not have the necessary IAM permissions to perform the requested DynamoDB operation. This is a common misconfiguration after deployments where the role or its attached policies are not updated to include the required DynamoDB actions (e.g., dynamodb:GetItem, dynamodb:PutItem). The 502 Bad Gateway from API Gateway is a direct consequence of the Lambda function failing internally due to this permission error.

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The Lambda function is timing out. Increase the timeout value in the Lambda configuration.

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The DynamoDB table is throttling requests. Enable auto-scaling for the table.

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The API Gateway request is too large. Set the payload size limit higher in API Gateway settings.

Question 6

A developer is deploying a Lambda function that processes messages from an SQS queue. The queue has a batch size of 10. To optimize cost and performance, the developer wants to minimize the number of Lambda invocations while ensuring that all messages are processed within the SQS visibility timeout. Which configuration should the developer use?

Accepted Answer

Set the Lambda function timeout to less than the SQS visibility timeout.. Setting the Lambda function timeout to less than the SQS visibility timeout ensures that the function completes (success or failure) before the message visibility timeout expires. This prevents the message from becoming visible again while the function is still running, which would cause duplicate invocations. If the function fails, the message remains in the queue and becomes visible again after the original visibility timeout, allowing for reprocessing without overlapping executions. This configuration keeps the number of invocations to one per batch for successful processing and avoids unintended duplicates, rather than adding extra retries.

Answer

Increase the SQS visibility timeout to 5 minutes and set Lambda timeout to 5 minutes.

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Configure the Lambda function to process messages asynchronously.

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Set the Lambda reserved concurrency to 1 to limit concurrent executions.

Question 7

A developer is using AWS CodeDeploy to deploy a new version of an application to an Auto Scaling group. The deployment fails because the new instances do not pass the health check. The developer wants to automatically roll back the deployment if the health check fails. Which CodeDeploy setting should be configured?

Accepted Answer

Enable automatic rollback in the deployment group configuration.. AWS CodeDeploy provides a built-in automatic rollback feature that can be configured at the deployment group level. When enabled, if a deployment fails (e.g., due to health check failures), CodeDeploy automatically reverts to the last known successful deployment, ensuring minimal downtime and manual intervention.

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Set the deployment configuration to AllAtOnce to speed up the process.

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Configure a lifecycle hook to terminate failing instances.

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Use a blue/green deployment strategy instead of in-place.

Question 8

A company runs a web application on EC2 instances behind an Application Load Balancer. The application uses sessions stored in an ElastiCache Redis cluster. Recently, users have been experiencing session timeouts and errors. The developer notices that the Redis cluster is running out of memory. What should the developer do to resolve this issue?

Accepted Answer

Enable the 'allkeys-lru' eviction policy in the Redis parameter group.. Enabling the 'allkeys-lru' eviction policy in the Redis parameter group allows Redis to automatically evict the least recently used keys when memory is full, preventing session timeouts and errors caused by out-of-memory conditions. This policy is specifically designed for use cases like session storage where losing old sessions is acceptable to free memory for new ones.

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Increase the session timeout in the application configuration.

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Reduce the number of EC2 instances behind the load balancer.

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Migrate from Redis to a Memcached cluster.

Question 9

A developer wants to store session state for a web application running on multiple EC2 instances. Which AWS service provides a fully managed, in-memory data store that is ideal for this use case?

Accepted Answer

Amazon ElastiCache for Redis. Amazon ElastiCache for Redis is the correct choice because it provides a fully managed, in-memory data store that is ideal for storing session state across multiple EC2 instances. Redis supports atomic operations, TTL-based key expiration, and high-speed reads/writes, making it perfect for session management where low-latency access and automatic data eviction are critical. Unlike disk-based stores, ElastiCache for Redis keeps session data in memory, ensuring sub-millisecond response times and seamless scaling as the web application grows.

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Amazon S3

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Amazon DynamoDB

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Amazon RDS for MySQL

Question 10

A developer is deploying an application using AWS Elastic Beanstalk. The application requires a relational database. Which THREE components are created by Elastic Beanstalk when you add a database to your environment?

Accepted Answer

A DB subnet group. When you add a database to an Elastic Beanstalk environment, Elastic Beanstalk automatically creates a DB subnet group, an Amazon RDS DB instance, and a security group for the database. The CloudFormation stack is already created as part of the environment's infrastructure, not specifically when adding the database. DynamoDB is not used for relational databases.

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An AWS CloudFormation stack

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An Amazon DynamoDB table

Question 11

A developer is building a serverless application using AWS Lambda to process events from Amazon S3. The Lambda function needs to persist data to an Amazon RDS MySQL database. Which of the following is the MOST secure way to pass database credentials to the Lambda function?

Accepted Answer

Store the credentials in AWS Secrets Manager and retrieve them in the Lambda function code.. AWS Secrets Manager provides a secure, auditable, and automated way to store and retrieve database credentials. The Lambda function can assume an IAM role with permissions to access the secret, and retrieve the credentials at runtime using the AWS SDK, avoiding hardcoding or insecure storage. This approach also supports automatic rotation of credentials, enhancing security.

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Store the credentials in an S3 bucket with server-side encryption and read them in the Lambda function.

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Use IAM database authentication for MySQL and assign an IAM role to the Lambda function.

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Hardcode the credentials as environment variables in the Lambda function configuration.

Question 12

A company runs a containerized application on Amazon ECS Fargate. The application writes logs to stdout. The operations team wants to centralize log monitoring and set up alarms for error patterns. What should a developer do to meet these requirements with minimal operational overhead?

Accepted Answer

Configure the ECS task definition to use the awslogs log driver and set the log group.. The awslogs log driver is the native, zero-configuration way to send container stdout/stderr to Amazon CloudWatch Logs from ECS Fargate. By specifying the awslogs log driver and a log group in the task definition, logs are automatically forwarded without any additional agents, code changes, or infrastructure, meeting the requirement for minimal operational overhead.

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Use Amazon Kinesis Data Firehose to stream logs to Amazon S3 and then to CloudWatch Logs.

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Modify the application code to use the AWS SDK for CloudWatch Logs to put log events.

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Install the CloudWatch agent in the container and configure it to send logs.

Question 13

A company is using AWS CodePipeline to automate deployments. The pipeline has a source stage that retrieves code from Amazon S3, a build stage using AWS CodeBuild, and a deploy stage using AWS CodeDeploy. The build stage is failing intermittently with errors related to missing dependencies. What should a developer do to ensure the build environment has all required dependencies?

Accepted Answer

Create a custom buildspec.yml file in the source code that installs the dependencies in the install phase.. The buildspec.yml file defines the build phases for AWS CodeBuild, including the install phase where you can specify commands to install dependencies (e.g., using package managers like pip, npm, or apt-get). By placing this file in the source code, the build environment automatically executes these commands on every build, ensuring all required dependencies are present and consistent across runs, which resolves intermittent failures caused by missing dependencies.

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Configure environment variables in CodePipeline to set dependency paths.

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Manually install dependencies on the CodeBuild build server each time.

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Use AWS CodeCommit as the source repository instead of S3.

Question 14

A developer is deploying a web application using AWS Elastic Beanstalk. The application uses a MySQL database. During deployment, the developer needs to apply database schema migrations. Which approach should the developer use to run database migrations as part of the Elastic Beanstalk deployment?

Accepted Answer

Use an .ebextensions configuration file to run a migration script during deployment.. Elastic Beanstalk supports .ebextensions configuration files that can execute custom commands or scripts during deployment. By placing a migration script (e.g., a shell script that runs `mysql` commands or a framework migration tool) in the `.ebextensions` directory and using the `commands` or `container_commands` key, the developer can ensure the migration runs automatically after the application is deployed but before the new environment serves traffic. This approach integrates the migration into the deployment lifecycle without external dependencies.

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Configure an RDS event subscription to trigger a Lambda function that runs migrations.

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Run the migration script as a scheduled task using CloudWatch Events.

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Use AWS CodeDeploy's AppSpec file to run the migration script.

Question 15

A developer is using Amazon DynamoDB to store session data for a web application. The application reads and writes a single item per user session. The traffic pattern shows occasional spikes. The developer wants to minimize read and write costs. Which DynamoDB capacity mode should the developer choose?

Accepted Answer

On-demand capacity. On-demand capacity mode is ideal for unpredictable traffic patterns with occasional spikes because it automatically scales read and write throughput based on actual usage, charging only for consumed operations. Since the application reads and writes a single item per session and experiences spikes, on-demand eliminates the need to provision for peak capacity, minimizing costs compared to over-provisioning.

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Reserved capacity

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Provisioned capacity with manual scaling

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Provisioned capacity with auto scaling