DVA-C02 Deployment Practice Test 14 — 15 Questions

Question 1

A developer is using AWS OpsWorks for Chef Automate to manage a stack. The developer needs to deploy a new application version to existing instances. Which OpsWorks feature should the developer use?

Accepted Answer

Recipes. To resolve the technology contamination and terminology mismatch, the stem should refer to 'AWS OpsWorks Stacks' instead of 'AWS OpsWorks for Chef Automate'. In AWS OpsWorks Stacks, you use Chef Recipes (specifically associated with the Deploy lifecycle event) to deploy new application versions to existing instances.

Answer

Custom JSON

Answer

Stacks

Answer

Layers

Question 2

A company is deploying a microservices-based application on Amazon ECS using Fargate. The application consists of three services: frontend, backend, and database. The database service uses Amazon Aurora Serverless. The frontend and backend services are deployed as separate ECS services. The company uses AWS CodePipeline for CI/CD. Each service has its own CodePipeline pipeline that builds a Docker image and pushes it to Amazon ECR, then updates the ECS service with the new image. Recently, the backend service deployment started causing intermittent errors. After investigation, the developer found that the backend service is being updated while the frontend service is still pointing to the old backend version, causing API incompatibility. The developer needs to ensure that the backend service is updated before the frontend service, and that both are updated atomically. The developer also wants to automate the update process using CodePipeline. What should the developer do?

Accepted Answer

Create a single pipeline with separate stages: first deploy backend, then after successful deployment, deploy frontend.. A single pipeline with sequential stages ensures the backend is deployed first, and the frontend deploys only after the backend is stable. Option A is wrong because triggers don't control order. Option B is wrong because manual approval is not atomic and can be error-prone. Option C is wrong because updating services is not atomic; they should be in one pipeline.

Answer

Add a manual approval step between the backend and frontend pipelines.

Answer

Create a single pipeline that deploys both services simultaneously by updating both ECS services in a single CodeDeploy deployment.

Answer

Configure the frontend pipeline to trigger after the backend pipeline completes using Amazon CloudWatch Events.

Question 3

A developer is deploying a static website to Amazon S3. The website uses client-side JavaScript to make API calls to an AWS Lambda function via Amazon API Gateway. The developer wants to enable cross-origin resource sharing (CORS) on the API Gateway to allow the S3 website to make requests. After enabling CORS on the API Gateway and redeploying the API, the browser still reports CORS errors. The developer checks the API Gateway configuration and sees that the OPTIONS method is not defined. The developer has already enabled CORS via the API Gateway console, which should have created the OPTIONS method. However, it did not appear. What should the developer do to resolve the issue?

Accepted Answer

Manually add an OPTIONS method to the API Gateway resource and configure the CORS headers in the integration response.. Enabling CORS via the API Gateway console should automatically create an OPTIONS method and configure the necessary headers. However, if the OPTIONS method did not appear, it indicates that the CORS configuration was not properly applied, possibly due to a console bug or incomplete setup. The developer must manually add an OPTIONS method to the API Gateway resource, configure the integration to return the appropriate CORS headers (e.g., Access-Control-Allow-Origin, Access-Control-Allow-Methods, Access-Control-Allow-Headers), and then redeploy the API. Option A is incorrect because changing the HTTP method does not resolve the CORS preflight request failure. Option B is incorrect because S3 bucket policies control access to S3 objects, not CORS for API Gateway requests. Option C is incorrect because while the Lambda function can return CORS headers for the actual API calls, the OPTIONS preflight request is handled by API Gateway, not Lambda, and the headers must be configured at the API Gateway level for the OPTIONS method.

Answer

Update the JavaScript in the website to use a different HTTP method.

Answer

Update the S3 bucket policy to allow cross-origin requests from any origin.

Answer

Modify the Lambda function to return CORS headers in its response.

Question 4

A company is using AWS CloudFormation to deploy a stack that includes an Amazon EC2 instance with an attached Amazon EBS volume. The developer wants to ensure that the EBS volume is deleted when the EC2 instance is terminated. The developer has set the DeletionPolicy attribute on the EBS volume resource to Delete. However, after terminating the EC2 instance through the console, the EBS volume is still present. The stack still exists. What is the most likely reason the volume was not deleted?

Accepted Answer

The DeletionPolicy attribute only takes effect when the CloudFormation stack is deleted, not when an individual resource is terminated.. The DeletionPolicy attribute on a CloudFormation resource only takes effect when the stack itself is deleted, not when an individual resource inside the stack is terminated or deleted. Even though the EC2 instance was terminated, the CloudFormation stack still exists, so the DeletionPolicy on the EBS volume does not apply. Option A is incorrect because DeleteOnTermination is a property of the EC2 instance's BlockDeviceMapping that controls whether the volume is deleted when the instance is terminated; it is separate from DeletionPolicy. Option C is incorrect because even if the volume were the root device, DeletionPolicy still would not trigger on instance termination. Option D is incorrect because regardless of how the instance was terminated (manually or through stack update), the DeletionPolicy only applies to stack deletion, not resource termination.

Answer

The EBS volume has a DeleteOnTermination attribute set to false.

Answer

The EBS volume is the root device of the EC2 instance.

Answer

The EC2 instance was terminated manually, not through a stack update.

Question 5

A company deploys a serverless application using AWS SAM. The application includes an API Gateway REST API and multiple Lambda functions. The developer wants to deploy a new version of the API with a canary release strategy, sending 10% of traffic to the new version initially. Which SAM template configuration should the developer use?

Accepted Answer

Set Type: Canary in the DeploymentPreference of the Lambda function and add CanarySetting: { Percent: 10 } under DeploymentPreference.. To implement a canary release strategy for a Lambda function using AWS SAM, you must configure the `DeploymentPreference` property under the `AWS::Serverless::Function` resource. AWS SAM integrates with AWS CodeDeploy to manage the traffic shifting. You must specify a predefined CodeDeploy configuration for the `Type` property, such as `Canary10Percent5Minutes` (which routes 10% of traffic to the new version for 5 minutes before shifting 100% of traffic). Additionally, you must specify the `AutoPublishAlias` property on the Lambda function, which tells SAM to create an alias and detect new deployments to trigger the CodeDeploy traffic shifting. Custom percentages like `Percent: 10` or `Type: Canary` are not valid configurations for Lambda deployment preferences in SAM.

Answer

Set CanarySetting: { Percent: 10 } in the API Gateway resource's properties.

Answer

Set Type: Canary and TrafficShiftType: Canary in the DeploymentPreference of the Lambda function.

Answer

Set Type: Canary in the DeploymentPreference of the Lambda function and add a Percentage: 10 property.

Question 6

A team uses AWS CodePipeline to deploy a microservices application to Amazon ECS. The pipeline has a Source stage (GitHub), a Build stage (CodeBuild), and a Deploy stage (ECS). During a deployment, the pipeline fails at the Deploy stage with the error: 'Action execution failed: Deployment failed. The service my-service has reached the maximum number of tasks.' The service is configured with a desired count of 2 and a maximum percent of 200%. What is the most likely cause of this failure?

Accepted Answer

There are already 4 tasks running for the service, which is the maximum allowed by the deployment configuration.. With a desired count of 2 and a maximum percent of 200%, ECS allows up to 4 tasks during a deployment (2 × 200% = 4). If there are already 4 tasks running (e.g., from a previous deployment that did not complete or a manual scaling action), the new deployment cannot start additional tasks because it would exceed the maximum allowed. Option A is incorrect because insufficient memory would cause a different error, such as a task failing to start. Option C is incorrect because a high minimum healthy percent would prevent task replacement but would not directly cause a 'maximum number of tasks' error. Option D is incorrect because the error is about task count, not EC2 instance limits.

Answer

The task definition references a memory value that exceeds the available container instance memory.

Answer

The service's minimum healthy percent is set too high, preventing new tasks from starting.

Answer

The pipeline is trying to deploy to an ECS cluster that has reached its Amazon EC2 instance limit.

Question 7

A developer is deploying a web application using AWS Elastic Beanstalk. The application requires a custom platform that is not provided by Elastic Beanstalk. The developer has created a custom platform using the Packer tool and has stored the platform artifacts in an Amazon S3 bucket. Which TWO steps are necessary to use this custom platform in Elastic Beanstalk? (Choose TWO.)

Accepted Answer

Define a custom platform version in the Elastic Beanstalk environment's configuration using a platform definition file.. Options A and D are correct. To use a custom platform in Elastic Beanstalk, the developer must first define a custom platform version in the environment's configuration using a platform definition file (option A). This file specifies the platform metadata and points to the artifacts stored in S3. Then, the developer must specify the custom platform ARN in the environment's configuration (option D) to associate the environment with that platform version. Option B is incorrect because the environment's platform is set by specifying a platform ARN, not by setting it to 'Custom' and providing an S3 URL directly. Option C is incorrect because a custom platform is defined by a Packer-based platform definition file, not by a Dockerfile; Dockerfiles are used for Docker platforms, not custom platforms. Option E is incorrect because the Packer template is used to build the custom platform artifacts, but it is not uploaded to Elastic Beanstalk; instead, the platform version resource points to the artifacts stored in S3.

Answer

Set the environment's platform to 'Custom' and provide the S3 URL of the platform artifacts.

Answer

Create a Dockerfile in the application source bundle to define the custom platform.

Answer

Upload the Packer template to the Elastic Beanstalk console.

Question 8

A company uses AWS CodeDeploy to manage deployments to an Amazon EC2 Auto Scaling group. The deployment group is configured with a blue/green deployment type. The developer notices that after a deployment, the old instances (blue environment) are terminated immediately after the new instances (green environment) pass health checks. The company wants to keep the old instances running for 30 minutes to allow for quick rollback if issues are detected. Which TWO configuration changes should the developer make to achieve this? (Choose TWO.)

Accepted Answer

Set the 'terminateBlueInstancesOnDeploymentSuccess' action to 'KEEP_ALIVE'.. Options A and C are correct. To keep old (blue) instances running for a specified period after a successful blue/green deployment, you must set the 'terminateBlueInstancesOnDeploymentSuccess' action to 'KEEP_ALIVE' (option A). This prevents immediate termination. Then, set the 'terminationWaitTimeInMinutes' to 30 (option C) to define the waiting period before termination. Option B is incorrect because 'WAIT' is not a valid value for the 'blueInstanceTermination' property; the correct property is 'terminateBlueInstancesOnDeploymentSuccess'. Option D is incorrect because 'originalSettings' is not a valid retention type. Option E is incorrect because 'waitTimeForBlueTermination' is not a valid property name; the correct property is 'terminationWaitTimeInMinutes'.

Answer

Set the 'blueInstanceTermination' property to 'WAIT'.

Answer

Set the 'blueInstanceTermination' property to 'originalSettings'.

Answer

Set the 'waitTimeForBlueTermination' to 30.

Question 9

A company is using AWS CodeCommit as a source repository for a CI/CD pipeline. The developer has set up AWS CodePipeline with a source stage that uses CodeCommit. The pipeline triggers automatically on changes to the repository. The developer wants to ensure that only changes to the 'main' branch trigger the pipeline. Which THREE configurations should the developer set in the CodePipeline source stage? (Choose THREE.)

Accepted Answer

Disable 'Poll for source changes'.. Disabling 'Poll for source changes' is necessary when using event-based change detection (CloudWatch Events) to trigger the pipeline. When you set 'Change detection' to 'Amazon CloudWatch Events' (option C), you must disable polling to avoid duplicate triggers and ensure the pipeline only responds to CloudWatch Events triggered by commits to the specified branch. This configuration ensures that only changes to the 'main' branch (set in option E) initiate the pipeline.

Answer

Set 'Output artifact format' to 'CodeCommit'.

Answer

Set 'Repository name' to 'main'.

Question 10

A company is deploying a containerized application on Amazon ECS using Fargate launch type. The application consists of multiple microservices, each deployed as a separate ECS service. The company uses AWS CodePipeline to automate deployments. The pipeline has a Source stage (CodeCommit), a Build stage (CodeBuild), and a Deploy stage (ECS). Recently, a deployment failed because the new task definition referenced an environment variable that was not available in the Parameter Store. The developer wants to prevent such failures in the future by validating the task definition before deployment. The developer has access to the AWS CLI and the AWS SDKs. The pipeline is configured to use CodeBuild for the build stage. What is the MOST efficient way to validate the task definition before deployment?

Accepted Answer

Add a step in the CodeBuild buildspec that runs 'aws ecs register-task-definition --cli-input-json file://taskdef.json --no-cli-pager --dry-run' to validate the task definition.. To validate the syntax and schema of an ECS task definition file (taskdef.json) before deployment, the developer can attempt to register it using the 'aws ecs register-task-definition' command during the Build stage in AWS CodeBuild. If the JSON file contains syntax errors, invalid parameters, or schema violations, the AWS CLI command will fail synchronously, causing the CodeBuild build stage to fail and preventing the pipeline from proceeding to the Deploy stage.

Option B is incorrect because 'aws ecs update-service' does not accept a local JSON file path for the '--task-definition' parameter; it requires an already registered task definition family or ARN. Furthermore, calling 'update-service' would trigger an actual deployment, bypassing the separation of concerns between the Build and Deploy stages.
Option C is incorrect because 'aws ecs run-task' does not accept a local JSON file path and would attempt to run an active task rather than just validating the definition.
Option D is incorrect because 'aws ecs describe-task-definition' is used to retrieve details of an already registered task definition and does not accept a local JSON file path.

Answer

Add a step in the CodeBuild buildspec that runs 'aws ecs update-service --service my-service --task-definition <task-def-arn>' to see if the service accepts the task definition.

Answer

Add a step in the CodeBuild buildspec that runs 'aws ecs run-task --task-definition <task-def-arn> --count 1' to test the task definition.

Answer

Add a step in the CodeBuild buildspec that runs 'aws ecs describe-task-definition --task-definition <task-def-arn>' to check if the task definition exists.

Question 11

A developer is deploying a web application on AWS Elastic Beanstalk. The application uses a relational database and requires a custom environment variable for the database connection string. The developer has created an Elastic Beanstalk environment and wants to set the environment variable securely without exposing it in the source code or configuration files. The developer also wants to ensure that the environment variable is available to the application instances at deployment time. What is the BEST way to achieve this?

Accepted Answer

Set the environment variable using the Elastic Beanstalk console or CLI by configuring environment properties.. The best because Elastic Beanstalk allows setting environment properties in the environment configuration, which are securely passed to the application instances and automatically injected as environment variables without exposing them in source code. This meets the requirement for secure, deployment-time availability. Option B (Parameter Store) is less suitable because the application must retrieve it at runtime, adding complexity and potential latency, and it is not automatically injected like environment properties. Option C is insecure as it exposes the connection string in source code. Option D is insecure because the file is stored in plain text within the source bundle.

Answer

Store the connection string in AWS Systems Manager Parameter Store and retrieve it from the application code at runtime.

Answer

Hardcode the connection string in the application code and commit it to the source repository.

Answer

Store the connection string in a file named 'env.txt' in the application source bundle and read it at application startup.

Question 12

A developer is using AWS CodeBuild to build and test a Java application. The buildspec.yaml file includes phases for install, pre_build, build, and post_build. The developer notices that the build fails intermittently due to network timeouts when downloading dependencies from an external repository. The developer wants to improve the reliability of the build by caching the dependencies. The build environment is Linux and the dependencies are stored in the /root/.m2 directory (Maven cache). The developer has an S3 bucket for caching. What should the developer add to the buildspec.yaml to enable caching?

Accepted Answer

Add a 'cache' section with 'paths' including '/root/.m2' and 'location' set to the S3 bucket name.. AWS CodeBuild allows caching using a 'cache' section in the buildspec.yaml file. By specifying the 'paths' with '/root/.m2' and the 'location' as the S3 bucket (using the bucket name), CodeBuild will cache the Maven dependencies between builds, reducing network timeouts. Option A is incorrect because manually copying to S3 in the install phase would not leverage CodeBuild's caching mechanism and would require additional scripting. Option B is incorrect because the 'artifacts' section is for output artifacts generated by the build, not for caching dependencies. Option D is incorrect because the 'env' section with Parameter Store is for storing environment variables or secrets, not for caching.

Answer

Add a 'phases' section with install commands to manually copy dependencies to S3.

Answer

Add an 'artifacts' section with 'files' including '/root/.m2/**/*' and 'location' set to the S3 bucket.

Answer

Add an 'env' section with 'parameter-store' variables to store the dependency paths.

Question 13

A company uses AWS CloudFormation to deploy infrastructure. The developer has created a stack that includes an Amazon RDS DB instance. The stack creation fails with a rollback, and the error message indicates that the DB instance could not be created because the DB instance identifier already exists. The developer has verified that there is no existing DB instance with that identifier in the account. The stack uses a custom resource to generate the DB instance identifier. The custom resource is a Lambda function that returns a unique identifier. The developer suspects that the custom resource is returning a stale value. What is the MOST likely cause of this issue?

Accepted Answer

The custom resource Lambda function has not been updated with the new code; the stack is using a previous version of the function.. The custom resource Lambda function may not have been updated with new code, causing the stack to use a previous version that returns a stale DB instance identifier. This stale identifier could conflict with an existing DB instance from a previous stack creation attempt. Option B is incorrect because CloudFormation does not reuse previous custom resource outputs based on stack name; each stack creation invokes the custom resource anew. Option C is incorrect because a random number generator without a seed would still produce different values on each invocation. Option D is incorrect because if the service token were incorrect, the custom resource would fail to invoke, leading to a different error about missing properties or invalid service token.

Answer

The stack is using the same stack name, and CloudFormation is reusing the previous custom resource output.

Answer

The custom resource Lambda function is returning the same value because it uses a random number generator without a seed.

Answer

The custom resource Lambda function is not being invoked during stack creation because the service token is incorrect.

Question 14

A developer is deploying a serverless application using AWS SAM. The application includes an API Gateway HTTP API and multiple Lambda functions. The developer wants to implement a gradual deployment strategy where 10% of traffic is shifted to the new version, and if no errors occur, the remaining traffic is shifted after 5 minutes. The developer has defined the deployment preference in the SAM template. However, after deploying, the developer notices that the traffic shift happens immediately and not gradually. The SAM template includes the following configuration for one of the Lambda functions:

DeploymentPreference:
  Type: Linear10PercentEvery5Minutes

The developer has confirmed that the Lambda function version is being updated. What is the MOST likely reason the gradual deployment is not working?

Accepted Answer

The API Gateway integration is pointing to the Lambda function without specifying a version or alias.. For gradual deployments to work with API Gateway HTTP API, the Lambda function must be integrated using the function's ARN with the version number (e.g., my-function:1), not the function name alone. If the integration uses the function name (without version), API Gateway always invokes the $LATEST version, bypassing the traffic shifting. Option A is incorrect because CodeDeploy is automatically used when DeploymentPreference is set in SAM. Option C is incorrect because the Lambda alias is created by SAM for traffic shifting; if the alias were not created, the deployment would fail. Option D is incorrect because the default version is $LATEST, but the issue is with how API Gateway invokes the function.

Answer

The developer did not create a Lambda alias for the function.

Answer

The developer did not enable canary deployment in the API Gateway stage.

Answer

The Lambda function is using the default version, which cannot be used with gradual deployments.

Question 15

A developer is using AWS CodeDeploy with a blue/green deployment strategy to update an application running on Amazon ECS with the Fargate launch type. After the new (green) task set is created and traffic is shifted to it, users immediately report errors when trying to write data. The developer discovers that the green task set is connecting to a different database than the blue task set. The database endpoints are configured in the ECS task definition. What is the simplest way to prevent this issue in future deployments?

Accepted Answer

Modify the blue/green deployment configuration to use the same database endpoint for both task sets by updating the environment variables in the task definition before deployment.. The issue stems from the green task set using a different database endpoint than the blue task set, which is configured via environment variables in the ECS task definition. By updating the task definition to use the same database endpoint before deployment, both task sets will connect to the same database, ensuring consistency during the traffic shift. This is the simplest fix as it requires no additional infrastructure or complex routing changes.

Answer

Create two separate Amazon RDS databases and use an Amazon Route 53 weighted routing policy to distribute traffic.

Answer

Use an Application Load Balancer (ALB) with stickiness to route each user to the correct task set.

Answer

Use AWS CloudFormation to create a new database stack for each deployment and update the task definition dynamically.