DVA-C02 Practice Test 19 — 15 Questions

Question 1

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?

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

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.

Answer

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

Answer

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

Answer

Use an Amazon RDS database to store session state.

Question 2

A developer is configuring an S3 bucket to host a static website. The bucket policy allows public read access. However, users receive a 403 Forbidden error when accessing the website. What is the most likely cause?

Accepted Answer

The bucket has 'Block all public access' settings enabled.. The 'Block all public access' settings in the S3 bucket's Permissions tab override any bucket policy that grants public read access. Even if the bucket policy explicitly allows s3:GetObject for Principal "*", enabling any of the four block public access settings (especially 'Block public access to buckets and objects granted through new public bucket policies' or 'Block public and cross-account access to buckets and objects through any public bucket policies') will cause S3 to reject all anonymous requests, resulting in a 403 Forbidden error when accessing the static website endpoint.

Answer

The bucket is located in a different AWS region than the website endpoint.

Answer

The bucket name does not match the domain name.

Answer

The bucket is not configured with CloudFront as a content delivery network.

Question 3

A company wants to allow cross-account access to an S3 bucket in Account A from a role in Account B. The S3 bucket policy in Account A allows the role's ARN. However, access is denied. What is the most likely missing step?

Accepted Answer

The role in Account B must have an IAM policy that allows the S3 actions.. Cross-account S3 access requires both a resource-based policy (the bucket policy in Account A) that grants access to the role ARN, and an identity-based policy (an IAM policy attached to the role in Account B) that explicitly allows the S3 actions. Without the IAM policy in Account B, the role lacks permission to perform the S3 operations, even though the bucket policy permits the access. This is a fundamental principle of AWS cross-account authorization: both the resource side and the principal side must grant the necessary permissions.

Answer

Add a bucket policy that denies access to all principals.

Answer

Disable block public access settings on the bucket.

Answer

Enable ACLs on the S3 bucket.

Question 4

A company wants to ensure that no Amazon S3 buckets in the AWS account can be made publicly accessible, even if a bucket policy or ACL is later configured to allow public access. Which AWS feature should the developer enable to enforce this at the account level?

Accepted Answer

S3 Block Public Access. S3 Block Public Access is the correct choice because it provides account-level settings that override any bucket-level policies or ACLs that would grant public access. When enabled at the account level, these settings apply to all current and future S3 buckets, effectively preventing any bucket from becoming publicly accessible regardless of subsequent configuration changes.

Answer

S3 Object Lock

Answer

S3 Transfer Acceleration

Answer

S3 Bucket Policy with Deny clause

Question 5

A developer is building a serverless application that processes user-submitted images. The images are uploaded to an S3 bucket, which triggers an AWS Lambda function that creates a thumbnail and stores it in another S3 bucket. The developer notices that sometimes the Lambda function is invoked multiple times for a single image upload. What should the developer configure to ensure idempotent processing?

Accepted Answer

Implement a DynamoDB table to track processed objects.. S3 event notifications can occasionally deliver duplicate events (at-least-once semantics). By storing the unique object key (or ETag) in a DynamoDB table with a TTL, the Lambda function can check if the object has already been processed and skip duplicate invocations, ensuring idempotent processing.

Answer

Enable S3 event notifications with a suffix filter.

Answer

Use an SQS queue to decouple S3 events.

Answer

Increase the Lambda function's timeout.

Question 6

A developer is using AWS SAM to define a serverless application. The application includes an AWS Lambda function that needs to access an Amazon DynamoDB table. The developer wants to grant the Lambda function the minimum required permissions to read and write items in the table. Which resource should the developer use to define the IAM permissions?

Accepted Answer

AWS::Serverless::Function Policies property. The AWS::Serverless::Function resource's Policies property allows you to attach IAM policies directly to the Lambda function's execution role in a declarative manner. By specifying a policy statement with dynamodb:GetItem, dynamodb:PutItem, etc., and the ARN of the DynamoDB table, you grant the minimum required permissions for read and write access without manually creating an IAM role. SAM automatically creates and associates the IAM role with the function, simplifying permission management.

Answer

AWS::DynamoDB::Table

Answer

AWS::IAM::Role

Answer

AWS::Lambda::Permission

Question 7

A company uses AWS CodeDeploy to deploy a web application to an Auto Scaling group. The deployment fails with the error 'The overall deployment failed because too many individual instances failed deployment, too few healthy instances are available for deployment, or some instances in your deployment group are experiencing problems.' The deployment group has a minimum of 2 instances and a maximum of 4. The deployment configuration is CodeDeployDefault.OneAtATime. What is the most likely cause of the failure?

Accepted Answer

The Auto Scaling group has only 2 instances, and one instance fails during deployment, leaving less than the required healthy instances.. The deployment configuration CodeDeployDefault.OneAtATime deploys to one instance at a time, and the deployment group has a minimum of 2 healthy instances. If one instance fails during deployment, only 1 healthy instance remains, which is below the minimum required threshold of 2. This causes CodeDeploy to stop the deployment and mark it as failed, as it cannot maintain the required number of healthy instances.

Answer

The deployment group's maximum instances is set to 4, which exceeds the number of instances in the Auto Scaling group.

Answer

The IAM role attached to the instances does not have sufficient permissions to download the revision from Amazon S3.

Answer

The revision is not properly zipped or the AppSpec file is missing.

Question 8

A company is using AWS CodePipeline to automate their CI/CD pipeline. The pipeline includes a stage that runs a set of integration tests using AWS CodeBuild. The tests require access to a database running on a private subnet in a VPC. The CodeBuild project is configured to use a managed compute image. How can the CodeBuild project access the database?

Accepted Answer

Configure the CodeBuild project to use a custom VPC with the appropriate subnet and security group.. CodeBuild projects using managed compute images run in an AWS-managed VPC by default, which cannot access resources in a customer VPC. By configuring the CodeBuild project to use a custom VPC with the appropriate subnet and security group, the build environment is launched directly into that VPC, enabling it to reach the database on the private subnet without needing a NAT gateway or internet access.

Answer

Place the CodeBuild project in a public subnet and use a NAT gateway to route traffic to the private subnet.

Answer

Set up a VPC peering connection between the CodeBuild VPC and the database VPC.

Answer

Create a VPC endpoint for the database service and attach it to the CodeBuild project.

Question 9

A developer is deploying a containerized application to Amazon ECS with the Fargate launch type using AWS CodeDeploy for blue/green deployments. The application is behind an Application Load Balancer (ALB). What is the minimum number of ALB target groups required for a blue/green deployment?

Accepted Answer

2. In a blue/green deployment with Amazon ECS (Fargate) and AWS CodeDeploy, the deployment process requires two distinct target groups: one for the 'blue' (current) environment and one for the 'green' (new) environment. CodeDeploy shifts traffic from the blue target group to the green target group during the deployment, allowing for instant rollback by switching back. A single target group cannot differentiate between the two environments, and three or more are unnecessary because the blue/green model only needs two active target groups at any time.

Answer

1

Answer

3

Answer

4

Question 10

A company uses AWS Elastic Beanstalk to deploy a web application. The environment is currently running a previous version. The developer uploads a new application version and deploys it to the environment. After the deployment, the environment health status turns 'Severe' and the new version is not accessible. The developer needs to quickly revert to the previous working version. What should the developer do?

Accepted Answer

Use the Elastic Beanstalk console to deploy the previous application version.. Elastic Beanstalk allows you to deploy a previous application version directly from the console or CLI without creating a new environment. This action replaces the current application version in the existing environment, restoring the previously working code and resolving the health status. It is the fastest and most straightforward way to revert while preserving the environment's configuration and resources.

Answer

Create a new environment with the previous version and swap CNAMEs.

Answer

Roll back the environment configuration to a previous saved configuration.

Answer

Terminate the environment and launch a new one with the previous version.

Question 11

A developer is deploying an application on Amazon ECS using the Fargate launch type. The application needs to read configuration data from an Amazon S3 bucket. How should the developer securely provide the S3 bucket name to the container at runtime?

Accepted Answer

Define an environment variable in the ECS task definition with the bucket name.. Defining an environment variable in the ECS task definition is the simplest and most secure way to inject the S3 bucket name into the container at runtime. Environment variables are passed to the container when it starts, and they can be stored in the task definition itself or referenced from AWS Secrets Manager or Systems Manager Parameter Store for sensitive values. This approach avoids hardcoding and keeps the configuration decoupled from the application code.

Answer

Hardcode the bucket name in the application code.

Answer

Use AWS Systems Manager Parameter Store and retrieve the bucket name at startup.

Answer

Store the bucket name in the container image's environment file.

Question 12

A developer is using AWS Elastic Beanstalk to deploy a web application. The application needs to store session state. Which configuration is MOST cost-effective and scalable?

Accepted Answer

Use an ElastiCache Memcached cluster. ElastiCache Memcached is the most cost-effective and scalable solution for storing session state because it is an in-memory cache designed for low-latency access, which is ideal for session data that must be frequently read and written. It scales horizontally by adding nodes, and its distributed nature ensures that session data persists across EC2 instance replacements, unlike local storage. This avoids the higher cost and overhead of RDS or the latency and eventual consistency issues of S3 for session management.

Answer

Use S3 to store session state

Answer

Use an RDS database to store session state

Answer

Store session state in the local file system of each EC2 instance

Question 13

A developer is deploying an application using AWS CloudFormation. The stack includes an Amazon RDS DB instance. To ensure secure credential management, which TWO actions should the developer take? (Choose TWO.)

Accepted Answer

Use AWS Systems Manager Parameter Store with a SecureString parameter for the password.. AWS Systems Manager Parameter Store with a SecureString parameter is correct because it allows you to securely store the RDS master password as an encrypted parameter and reference it in the CloudFormation template using the `resolve:ssm` or `resolve:ssm-secure` dynamic reference. This avoids hardcoding the password in the template or exposing it in plaintext, while still enabling automated deployment.

Answer

Hardcode the master password in the CloudFormation template.

Answer

Use IAM database authentication to manage credentials.

Answer

Leave the master password empty so that CloudFormation generates a random password.

Question 14

A developer is troubleshooting an AWS Lambda function that processes large CSV files (up to 1 GB) uploaded to an Amazon S3 bucket. The function uses Python and the pandas library to perform data transformations. Recently, the function started timing out on large files. CloudWatch Logs show that the function's execution time is close to the 15-minute Lambda timeout, and memory utilization peaks at around 80% of the configured 3,008 MB. The function has not been modified in months. Which action will most likely resolve the timeout issue without requiring code changes?

Accepted Answer

Increase the memory allocation of the Lambda function to the maximum available (10,240 MB). Increasing the memory allocation to the maximum (10,240 MB) proportionally increases the CPU and network throughput allocated to the Lambda function, which directly reduces execution time for CPU-bound pandas operations. Since memory utilization is only at 80% of the current 3,008 MB, the bottleneck is likely CPU, not memory, and Lambda's CPU scales linearly with memory configuration. This action resolves the timeout without any code changes.

Answer

Increase the function timeout to the maximum allowed (900 seconds is already the max)

Answer

Use S3 Select to filter columns and rows before invoking the Lambda function

Answer

Increase the batch size of the S3 event notification to invoke the function with multiple files

Question 15

A company is building a serverless application using AWS Lambda and Amazon DynamoDB. The Lambda function processes user uploads from Amazon S3 and stores metadata in DynamoDB. The function is experiencing high latency during peak hours. Which action would MOST improve the performance without increasing the function timeout?

Accepted Answer

Increase the DynamoDB table's provisioned read and write capacity.. Increasing the DynamoDB table's provisioned read and write capacity directly addresses the root cause of high latency during peak hours: throttling due to insufficient throughput. When the Lambda function's write requests exceed the table's capacity, DynamoDB throttles them, causing retries and increased latency. Raising the capacity allows DynamoDB to handle the burst of metadata writes without throttling, reducing response times without requiring a longer function timeout.

Answer

Increase the Lambda reserved concurrency.

Answer

Move the Lambda function into a VPC with a DynamoDB VPC endpoint.

Answer

Enable DynamoDB Accelerator (DAX) for the table.