DVA-C02 Deployment Practice Test 17 — 15 Questions

Question 1

A company wants to deploy a serverless application using AWS Lambda and API Gateway. The deployment process must support automatic rollbacks if the new version fails CloudWatch alarms. Which AWS service should be used to orchestrate this deployment?

Accepted Answer

AWS CodeDeploy. Option D is correct. AWS CodeDeploy can be used with Lambda to perform canary or linear deployments and automatically roll back based on CloudWatch alarms. Option A is wrong because CloudFormation does not natively support canary deployments or automatic rollback based on alarms for Lambda. Option B is wrong because AWS Elastic Beanstalk is for web applications, not serverless. Option C is wrong because AWS CodePipeline orchestrates build/test/deploy but does not handle canary deployments and rollback itself.

Answer

AWS Elastic Beanstalk

Answer

AWS CloudFormation with a change set

Answer

AWS CodePipeline

Question 2

A DevOps engineer is implementing a blue/green deployment for a microservice running on Amazon ECS with Fargate. The service is fronted by an Application Load Balancer. During deployment, the new task set fails health checks, but the deployment does not automatically roll back. What is the MOST likely reason?

Accepted Answer

The ECS service deployment controller is set to 'ECS' instead of 'CODE_DEPLOY'.. Option A is correct. For blue/green deployments on ECS, you must specify a deployment controller type of 'CODE_DEPLOY' to use CodeDeploy and enable automatic rollback. If the controller is 'ECS' (the default), the deployment is managed by ECS and does not support automatic rollback on health check failures in blue/green mode. Option B is wrong because ECS does roll back if health checks fail when using ECS deployment controller with rolling update, but not for blue/green. Option C is wrong because CodeDeploy is not used if deployment controller is not CODE_DEPLOY. Option D is wrong because health check grace period delays health checks but does not prevent rollback if checks fail after grace period.

Answer

The CodeDeploy application and deployment group are not configured for automatic rollback.

Answer

The health check grace period is set too high.

Answer

The ECS service is configured with a 'minimum healthy percent' of 100 percent.

Question 3

A company uses AWS CodePipeline to deploy a static website to Amazon S3. The pipeline has a source stage from CodeCommit, a build stage using CodeBuild, and a deploy stage that uses S3 deployment action. The website is served via Amazon CloudFront. After a successful pipeline run, the updated files are in S3, but CloudFront still serves old content. What is the MOST efficient solution?

Accepted Answer

Add a post-deploy invalidation step in CodePipeline to create a CloudFront invalidation.. Option C is correct. The easiest and most efficient way is to add a CloudFront invalidation step in the pipeline to invalidate the cache after the S3 deploy. Option A is wrong because reducing TTL is not immediate and still may serve stale content. Option B is wrong because updating the S3 bucket policy does not affect CloudFront cache. Option D is wrong because manually invalidating is one-time but not automated for future deployments.

Answer

Manually create a CloudFront invalidation after each deployment.

Answer

Reduce the CloudFront distribution's default TTL to 0.

Answer

Update the S3 bucket policy to allow public read access.

Question 4

A team uses AWS CloudFormation to manage infrastructure. They want to deploy a stack that includes an Amazon RDS DB instance. During deployment, the stack creation fails because the DB instance creation times out. The team wants to ensure that subsequent stack creation attempts do not recreate the DB instance from scratch but instead continue from the failed state. Which CloudFormation feature should they use?

Accepted Answer

Use a CloudFormation custom resource to check for an existing DB instance and create it only if it does not exist.. Option B is correct. CloudFormation stack creation rollback triggers with '--on-failure DO_NOTHING' or '--disable-rollback' will leave the failed resources in place so they can be resumed? Actually, CloudFormation does not support resuming a failed stack creation; it will roll back and delete resources. To avoid this, you can use a custom resource to check if the DB instance already exists, but the question asks for a feature to continue from failed state. The best approach is to use a custom resource or separate stack for the DB instance. Among options, only 'Custom resource' (Option A) can handle such logic, but the correct answer is B: Use a custom resource to check for existing DB instance and skip creation if it exists. However, Option A is also custom resource. Let's re-evaluate: The feature that allows you to conditionally create resources based on existing resources is 'Conditions' but that requires knowing the DB instance ID. 'Custom resource' can query existing DB and return a value to use in conditions. So Option B is correct. Option A (WaitCondition) is for signaling completion, not for conditional creation. Option C (Stack policy) protects resources but does not help with continuation. Option D (Change sets) are for updates, not creation rollback.

Answer

Use a CloudFormation WaitCondition to pause stack creation until the DB instance is available.

Answer

Create the DB instance using a separate CloudFormation stack and reference it using Fn::ImportValue.

Answer

Apply a stack policy that prevents the DB instance from being deleted during stack updates.

Question 5

A company is deploying a containerized application on Amazon ECS using the Fargate launch type. The deployment must ensure zero downtime. Which ECS deployment configuration should be used?

Accepted Answer

Blue/green deployment using AWS CodeDeploy. Option D is correct. Blue/green deployment with CodeDeploy allows you to shift traffic gradually and automatically roll back if issues arise, ensuring zero downtime. Option A is wrong because rolling update can cause downtime if not configured properly? Actually rolling update can also achieve zero downtime if you have enough capacity, but the question asks for config that ensures zero downtime, and blue/green is more reliable. Option B is wrong because 'DAEMON' scheduling strategy is for running one task per instance, not for zero-downtime deployment. Option C is wrong because 'REPLICA' is a task placement strategy, not a deployment type.

Answer

Rolling update with a minimum healthy percent of 50% and maximum percent of 200%

Answer

Set the task placement strategy to REPLICA

Answer

Use the DAEMON scheduling strategy with a deployment circuit breaker

Question 6

A developer is using AWS SAM to deploy a serverless application. The SAM template defines an API Gateway REST API and several Lambda functions. During deployment, the developer receives an error: 'Resource creation cancelled' for the API Gateway resource. The developer has sufficient IAM permissions. What is the MOST likely cause?

Accepted Answer

A stack policy is preventing the creation of the API Gateway resource.. Option C is correct. AWS SAM uses AWS CloudFormation to deploy resources. If a resource creation is cancelled, it often indicates a stack policy that prevents creation or modification of certain resources. Option A is wrong because a missing AWS::Serverless::Api would cause a different error. Option B is wrong because invalid YAML would cause a template validation error. Option D is wrong because Lambda function limit would cause a different error.

Answer

The AWS account has reached the limit of API Gateway REST APIs.

Answer

The SAM template has a syntax error in the YAML file.

Answer

The SAM template does not include an AWS::Serverless::Api resource.

Question 7

A company uses AWS CodeDeploy to deploy an application to EC2 instances. 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.' The deployment group consists of 4 EC2 instances. The deployment configuration is 'CodeDeployDefault.OneAtATime'. The CodeDeploy agent logs on the failed instance show: 'Error: Script at specified location: scripts/install_dependencies.sh failed with exit code 1.' What should the developer do to resolve this issue?

Accepted Answer

Review the install_dependencies.sh script for errors and correct them.. Option A is correct. The script failed with exit code 1, indicating a bug in the script. The developer should fix the script based on the logs. Option B is wrong because the deployment configuration is already OneAtATime; changing to AllAtOnce would make it worse. Option C is wrong because increasing instance count does not fix the script error. Option D is wrong because the error is in the script, not the agent.

Answer

Change the deployment configuration to 'CodeDeployDefault.AllAtOnce'.

Answer

Reinstall the CodeDeploy agent on the failed instance.

Answer

Increase the number of EC2 instances in the deployment group.

Question 8

A developer is deploying a web application using AWS Elastic Beanstalk. The application experiences high traffic during peak hours. The developer wants to ensure that the environment can scale out quickly without manual intervention. Which Elastic Beanstalk configuration should be used?

Accepted Answer

Configure Auto Scaling triggers based on CloudWatch alarms.. Option B is correct. Auto Scaling triggers based on CloudWatch alarms allow automatic scaling. Option A is wrong because fixed number of instances does not scale. Option C is wrong because time-based scaling is not dynamic. Option D is wrong because manual scaling is not automatic.

Answer

Use a scheduled scaling action to increase capacity during peak hours.

Answer

Manually add EC2 instances during peak hours.

Answer

Set the environment to use a fixed number of EC2 instances.

Question 9

Which TWO actions can be taken to enable automatic rollback for an AWS CloudFormation stack update that fails? (Select TWO.)

Accepted Answer

Specify a CloudWatch alarm in the '--rollback-configuration' parameter during stack update.. Options A and C are correct. The '--rollback-configuration' parameter can specify CloudWatch alarm thresholds that trigger rollback. Option C: Setting '--disable-rollback' to false (i.e., not disabling rollback) means rollback is enabled. Option B is wrong because '--on-failure' is only for stack creation, not update. Option D is wrong because a stack policy does not control rollback behavior. Option E is wrong because change sets do not enable automatic rollback.

Answer

Set the '--on-failure' parameter to 'ROLLBACK' during stack update.

Answer

Use a change set to review the changes before updating.

Answer

Apply a stack policy that denies updates to critical resources.

Question 10

Which THREE components are required to perform a blue/green deployment of an application running on Amazon ECS using AWS CodeDeploy? (Select THREE.)

Accepted Answer

An Application Load Balancer. Options A, B, and D are correct. CodeDeploy requires a CodeDeploy application and deployment group. An ECS service with a load balancer is also required. Option C is wrong because an ECS cluster is required, but the question asks for components, and the cluster is implicit; however, the deployment group references the ECS service, so the cluster is needed. But among options, A, B, D are explicitly required. Option E is wrong because a target tracking scaling policy is not required for blue/green deployment.

Answer

An Amazon ECS cluster

Answer

A target tracking scaling policy

Question 11

Which TWO strategies can be used to reduce the risk of a failed deployment when using AWS CodeDeploy? (Select TWO.)

Accepted Answer

Configure automatic rollback based on CloudWatch alarms.. Options B and D are correct. Gradual traffic shifting (canary or linear) and automatic rollback based on CloudWatch alarms reduce risk. Option A is wrong because deploying to all instances at once increases risk. Option C is wrong because skipping health checks increases risk. Option E is wrong because manual approval gate introduces delay but does not reduce risk of failure; it can help catch issues but not specifically reduce deployment failure risk.

Answer

Disable health checks to prevent false positives.

Answer

Require a manual approval step before deployment.

Answer

Deploy to all instances at once to ensure consistency.

Question 12

A developer deploys a new version of an AWS Lambda function using the AWS CLI. The deployment fails with a 'ResourceConflictException' error. What is the most likely cause?

Accepted Answer

Another deployment is currently in progress for the same Lambda function.. The error occurs when trying to update a Lambda function's code while a deployment is in progress or when the function's reserved concurrency is being modified. Option B is correct because publishing a new version during an active deployment causes a conflict. Options A, C, and D are incorrect because missing IAM roles, incorrect handler names, or exceeding memory limits cause different errors.

Answer

The function's handler name is incorrect in the deployment package.

Answer

The Lambda function's IAM role is missing necessary permissions.

Answer

The Lambda function's memory limit is set too low for the deployment package.

Question 13

A company uses AWS CodeDeploy to deploy a web application to an Auto Scaling group. The deployment fails, and the rollback is triggered. However, the rollback also fails. What is a likely cause?

Accepted Answer

The rollback deployment uses an AppSpec file that references a lifecycle hook that does not exist in the current environment.. Option D is correct because if the rollback tries to deploy the previous version, but that version's AppSpec file references a hook that no longer exists in the environment (e.g., a previously deleted directory), the rollback fails. Options A, B, and C are incorrect: insufficient capacity would cause the original deployment to fail differently, a misconfigured target group would affect traffic but not rollback, and a missing S3 bucket would cause the original deployment to fail, not the rollback specifically.

Answer

The target group for the load balancer is not properly configured.

Answer

The Amazon S3 bucket containing the deployment artifacts is missing.

Answer

The Auto Scaling group does not have sufficient capacity to run the rollback.

Question 14

A DevOps engineer is designing a CI/CD pipeline for a microservices application. The team wants to deploy updates to the production environment gradually and automatically roll back if health checks fail. Which AWS service and deployment configuration should the engineer use?

Accepted Answer

Use AWS CodeDeploy with a canary deployment and a CloudWatch alarm to trigger automatic rollback.. Option B is correct because AWS CodeDeploy with a canary deployment allows gradual traffic shifting and automatic rollback on CloudWatch alarm failure. Option A is incorrect because CloudFormation with a blue/green deployment requires manual rollback. Option C is incorrect because Elastic Beanstalk with rolling updates does not support canary-based traffic shifting. Option D is incorrect because CodePipeline alone does not handle deployment strategies or health check-based rollbacks.

Answer

Use AWS CloudFormation with a blue/green deployment and a CloudWatch alarm to trigger rollback.

Answer

Use AWS Elastic Beanstalk with a rolling update and a CloudWatch alarm to trigger rollback.

Answer

Use AWS CodePipeline with a manual approval step and a CloudWatch alarm to trigger rollback.

Question 15

A developer is deploying a serverless application using the AWS Serverless Application Model (SAM). The developer runs 'sam deploy' and receives an error: 'Error: Failed to create changeset for the stack.' What is a common cause of this error?

Accepted Answer

The SAM template contains a syntax error.. Option C is correct because the SAM template must be valid JSON or YAML; malformed syntax causes the changeset creation to fail. Options A, B, and D are incorrect: missing S3 bucket causes a different error, insufficient IAM permissions cause an authorization error, and CodeDeploy is not involved in SAM deployments.

Answer

The S3 bucket specified for artifacts does not exist.

Answer

The IAM user does not have permission to create CloudFormation stacks.

Answer

AWS CodeDeploy is not configured for the application.