DVA-C02 Development with AWS Services Practice Test 23 — 15 Questions

Question 1

A developer is building a serverless application using AWS Lambda to process images uploaded to an S3 bucket. The Lambda function needs to resize the image and store the result in another S3 bucket. The developer notices that the Lambda function fails intermittently with timeout errors for large images. What is the MOST efficient solution to resolve this issue?

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

Accepted Answer

Increase the Lambda function timeout and memory allocation to accommodate larger images.. Increasing the Lambda function timeout and memory allocation directly addresses the root cause of the failure: large images require more processing time and memory. Lambda's CPU and I/O throughput scale proportionally with allocated memory, so raising both parameters provides the necessary resources to complete the resize operation within the function's execution environment.

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Limit the S3 event notification to only trigger for images smaller than 5 MB.

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Refactor the Lambda function to use multi-threading for parallel processing of image chunks.

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Use AWS Step Functions to orchestrate the image processing in smaller steps.

Question 2

A company runs a containerized application on Amazon ECS using Fargate launch type. The application needs to read and write files to a shared file system across multiple tasks. The development team wants a solution that provides high throughput and is POSIX-compliant. Which storage solution should the team use?

Accepted Answer

Amazon EFS. Amazon EFS is the correct choice because it provides a fully managed, POSIX-compliant shared file system that can be mounted concurrently by multiple Amazon ECS tasks using the Fargate launch type. EFS uses the NFSv4.1 protocol, supports high throughput (up to 10 GB/s with Bursting or Provisioned Throughput modes), and automatically scales storage capacity as files are added or removed, making it ideal for shared read/write workloads across containers.

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Amazon S3 with mountpoint-s3

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Amazon EBS with multi-attach enabled

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Amazon FSx for Windows File Server

Question 3

A developer needs to store application configuration data (key-value pairs) that can be accessed by multiple microservices running on EC2 instances. The configuration data changes infrequently but must be retrievable with low latency. Which AWS service should the developer use?

Accepted Answer

AWS Systems Manager Parameter Store. AWS Systems Manager Parameter Store is designed specifically to store configuration data (such as database strings, license codes, or general key-value pairs) and secrets. It provides a centralized, secure, and hierarchical store that can be easily accessed by EC2 instances and microservices with low latency. Standard parameters are free of charge, making it the ideal choice for infrequently changing configuration data.

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AWS AppConfig

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Amazon S3

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Amazon DynamoDB

Question 4

A company is using AWS Lambda to process messages from an Amazon SQS queue. The Lambda function is configured with a reserved concurrency of 10. The SQS queue receives a burst of 1000 messages. The Lambda function processes each message in about 5 seconds. What is the most likely behavior of the system?

Accepted Answer

Lambda processes up to 10 messages concurrently, and the rest remain in the queue until processing capacity is available.. Lambda's reserved concurrency of 10 caps the maximum number of concurrent executions. When the SQS queue receives 1000 messages, Lambda polls the queue and invokes the function with up to 10 messages at a time (based on batch size, default 1). The remaining messages stay in the queue and are retried after the visibility timeout expires, as Lambda processes messages in batches limited by the reserved concurrency.

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Lambda rejects the messages and sends them to the dead-letter queue.

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Lambda automatically scales up to 1000 concurrent executions to process all messages quickly.

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Lambda increases the reserved concurrency to accommodate the burst.

Question 5

A company is running a monolithic application on an EC2 instance. The application currently stores session state in local memory on the instance. The company plans to scale the application horizontally by adding more instances behind a load balancer. What change is required to ensure that session state is preserved across requests?

Accepted Answer

Use Amazon ElastiCache to store session state externally.. Amazon ElastiCache provides a managed, in-memory caching service (e.g., Redis or Memcached) that can store session state externally. By moving session data out of the EC2 instance's local memory and into a shared, low-latency data store, all instances behind the load balancer can access the same session state, ensuring persistence across requests regardless of which instance handles the request.

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Store session data in Amazon S3 and retrieve it on each request.

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Increase the EC2 instance size to handle more sessions per instance.

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Use an Amazon RDS database to store session state.

Question 6

A developer is creating an AWS Lambda function that processes events from an Amazon S3 bucket. The function writes logs to Amazon CloudWatch Logs. The developer wants to ensure that the Lambda function has the minimum required permissions. Which IAM policy should be attached to the Lambda execution role?

Accepted Answer

A policy that includes 'logs:CreateLogGroup', 'logs:CreateLogStream', 'logs:PutLogEvents', and 's3:GetObject' on the specific bucket.. It grants the minimum required permissions for the Lambda function to read objects from the specific S3 bucket (s3:GetObject) and to write logs to CloudWatch Logs (logs:CreateLogGroup, logs:CreateLogStream, logs:PutLogEvents). The s3:GetObject action is necessary to process events from S3, and the three logs actions are the minimum needed for the Lambda runtime to create a log group, create a log stream, and write log events. This policy follows the principle of least privilege by scoping permissions to the specific bucket and avoiding wildcards.

Answer

A policy that includes 'logs:CreateLogStream', 'logs:PutLogEvents', and 's3:*' on the bucket.

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A policy that includes 'logs:*' and 's3:*' on the bucket.

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A policy that includes 'logs:PutLogEvents' and 's3:ListBucket' on the bucket.

Question 7

A developer is building a serverless application and wants to invoke an AWS Lambda function every hour to perform a cleanup task. Which AWS service should the developer use to schedule the invocation?

Accepted Answer

Amazon EventBridge (CloudWatch Events). Amazon EventBridge (formerly CloudWatch Events) is the correct service for scheduling AWS Lambda invocations on a recurring basis. It provides a cron or rate expression to trigger a Lambda function at a defined interval, such as every hour, without the need for managing any servers or additional infrastructure.

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AWS Step Functions

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Amazon SNS

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Amazon SQS

Question 8

A developer is designing a system that requires processing of streaming data from IoT devices in real time. The processed data will be stored in an S3 bucket for analytics. Which AWS services should the developer use together to build this solution? (Choose TWO.)

Accepted Answer

Amazon Kinesis Data Firehose. Amazon Kinesis Data Streams is a scalable real-time data streaming service that ingests and processes streaming data from IoT devices in real time. It allows developers to build custom applications that consume and analyze the data as it arrives. Amazon Kinesis Data Firehose is a fully managed service that reliably loads streaming data into Amazon S3 for analytics, handling buffering, compression, and partitioning. Together, Data Streams provides real-time processing capabilities while Firehose automates delivery to S3, making them a complementary pair for this solution.

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AWS Lambda

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Amazon S3

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Amazon SQS

Question 9

A company has a web application running on Amazon ECS with Fargate launch type. The application needs to store and retrieve user session data. The sessions are small and require very low latency access. The development team wants a fully managed solution. Which storage options meet these requirements? (Choose TWO.)

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is correct because it is a fully managed NoSQL key-value database that provides single-digit millisecond latency for read and write operations, making it ideal for storing small session data with low latency requirements. It scales automatically and requires no server management, aligning with the fully managed requirement and the Fargate launch type's serverless nature.

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Amazon S3

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Amazon EFS

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Amazon RDS for PostgreSQL

Question 10

A developer is deploying a serverless application using the AWS Serverless Application Model (SAM). The application consists of an API Gateway, Lambda functions, and a DynamoDB table. The developer wants to define and deploy this infrastructure as code. Which files and tools are required? (Choose THREE.)

Accepted Answer

aws cloudformation deploy command. The AWS SAM template file (template.yaml) is required to define the serverless application resources. The `aws cloudformation package` command uploads local artifacts (such as Lambda deployment packages) to an S3 bucket and returns a copy of the template with references to the S3 object locations. The `aws cloudformation deploy` command then provisions the stack using the processed template. Together, these three are essential for deploying a SAM application using CloudFormation commands. While SAM CLI provides convenient wrappers like `sam package` and `sam deploy`, the underlying CloudFormation commands can also be used directly.

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Terraform configuration files

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AWS CLI with aws lambda update-function-code command

Question 11

A developer is investigating why an AWS Lambda function is not writing logs to CloudWatch Logs. The function has been invoked multiple times, but the log group shows 0 stored bytes. What is the most likely cause?

Accepted Answer

The Lambda execution role lacks permissions to write to CloudWatch Logs.. The most likely cause is that the Lambda execution role lacks the necessary IAM permissions to write logs to CloudWatch Logs. Without permissions such as `logs:CreateLogGroup`, `logs:CreateLogStream`, and `logs:PutLogEvents`, the Lambda function cannot create the log group or stream, nor can it write log events, resulting in 0 stored bytes despite successful invocations.

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The CloudWatch Logs log group does not exist.

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The Lambda function is failing before any logging code is executed.

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The Lambda function is configured to use a different log group name.

Question 12

A company is using AWS Lambda functions to process events from Amazon S3. The functions are writing logs to CloudWatch Logs. Recently, they noticed that some logs are missing and the functions are experiencing throttling errors. What is the MOST likely cause?

Accepted Answer

The Lambda function's reserved concurrency is set to a low value.. The most likely cause of throttling errors is that the Lambda function's reserved concurrency is set too low. When a Lambda function's reserved concurrency limit is reached, additional invocation requests are throttled, resulting in missing logs. Option A is incorrect because log group retention affects log storage, not Lambda throttling. Option C is incorrect because IAM permissions affect the ability to write logs, not throttling. Option D is incorrect because while S3 can send many events, Lambda's concurrency limit is the direct cause of throttling.

Answer

The CloudWatch Logs log group retention policy is set too low.

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The Lambda function's IAM role lacks permissions to write to CloudWatch Logs.

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The S3 bucket is sending too many event notifications.

Question 13

A developer wants to deploy a containerized application on AWS. The application requires persistent storage that can be accessed by multiple containers running on different EC2 instances. Which AWS service should the developer use?

Accepted Answer

Amazon Elastic File System (EFS). Amazon EFS provides a fully managed, scalable, and elastic NFS file system that can be mounted concurrently on multiple EC2 instances across different Availability Zones. This makes it the ideal choice for a containerized application requiring shared persistent storage accessible by multiple containers running on different instances, as it supports the NFSv4.1 and NFSv4.0 protocols for simultaneous access.

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Amazon Elastic Block Store (EBS)

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Amazon Simple Storage Service (S3)

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Amazon DynamoDB

Question 14

A developer is building a real-time chat application using WebSocket APIs in Amazon API Gateway. The backend is an AWS Lambda function that stores connection IDs in an Amazon DynamoDB table. After a few days, the application stops working for new users. The developer checks CloudWatch Logs and sees that the Lambda function is returning 'AccessDeniedException' when calling DynamoDB. What is the MOST likely cause?

Accepted Answer

The DynamoDB table was recreated and the Lambda function's IAM role still references the old table ARN.. The most likely cause is that the DynamoDB table was recreated, which changes its ARN. The Lambda function's IAM role still references the old table ARN, so when the function attempts to perform DynamoDB operations (e.g., PutItem for storing connection IDs), the request is denied because the role no longer has permissions on the new table. This is a common issue when infrastructure is rebuilt without updating IAM policies.

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The Lambda function code was updated but the IAM role was not reattached.

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The Lambda function uses an outdated AWS SDK version.

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The API Gateway route was updated without redeploying the API.

Question 15

A developer is creating a CI/CD pipeline for a serverless application using AWS CodePipeline. The application consists of an AWS Lambda function, an Amazon API Gateway REST API, and an Amazon DynamoDB table. Which action should the developer take to automate the deployment of the API Gateway updates?

Accepted Answer

Use AWS CloudFormation to define and deploy the API Gateway.. AWS CloudFormation provides infrastructure as code (IaC) capabilities that allow you to define the entire API Gateway configuration, including resources, methods, integrations, and deployment stages, in a template. When integrated with CodePipeline, CloudFormation can automatically create or update the API Gateway and trigger a deployment as part of the CI/CD pipeline, ensuring consistent and repeatable deployments without manual intervention.

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Use AWS Lambda to update the API Gateway configuration.

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Store the API Gateway Swagger file in Amazon S3 and trigger a deployment.

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Use AWS CodeBuild to compile and deploy the API Gateway configuration.