DOP-C02 Resilient Cloud Solutions Practice Test 17 — 15 Questions

Question 1

A company's application runs on Amazon EC2 instances in an Auto Scaling group. The application writes logs to local instance storage. The operations team needs to ensure logs are not lost during instance termination or scaling events. What should be done?

Accepted Answer

Install the CloudWatch Logs agent on each instance and stream logs to CloudWatch Logs.. Configuring the CloudWatch Logs agent to stream logs to CloudWatch Logs in real time ensures logs are centralized and not lost.

Answer

Increase the size of the instance store volumes.

Answer

Use an Amazon EFS file system and mount it to each instance for log storage.

Answer

Configure the Auto Scaling group to terminate instances after logs are copied to S3.

Question 2

A company uses Amazon Route 53 for DNS. They want to ensure that if their primary website endpoint fails, traffic is automatically routed to a secondary endpoint in a different Region. Which routing policy should be used?

Accepted Answer

Failover routing. Failover routing policy allows you to configure an active-passive failover setup.

Answer

Latency routing

Answer

Simple routing

Answer

Weighted routing

Question 3

A company is building a serverless application using AWS Lambda, Amazon API Gateway, and Amazon DynamoDB. The application must be resilient to sudden spikes in traffic without manual intervention. Which combination of services should be used?

Accepted Answer

API Gateway with throttling, Lambda with reserved concurrency, and DynamoDB auto scaling.. API Gateway with throttling and Lambda with reserved concurrency help manage spikes. DynamoDB auto scaling adjusts capacity.

Answer

API Gateway with usage plans, Lambda with provisioned concurrency, and DynamoDB on-demand.

Answer

API Gateway with WAF, Lambda with function URLs, and DynamoDB Accelerator (DAX).

Answer

API Gateway with caching, Lambda with no concurrency limits, and DynamoDB global tables.

Question 4

A company is designing a resilient architecture for a web application that uses Amazon RDS for MySQL. The application must be able to withstand the loss of an entire AWS Region. Which TWO actions should the company take?

Accepted Answer

Configure automated backups to be copied to another Region.. Cross-Region Read Replica provides a standby in another Region for failover. Cross-Region automated backup copy allows recovery from backups in another Region.

Answer

Use RDS Proxy to pool database connections.

Answer

Enable Multi-AZ deployment for the RDS instance.

Answer

Enable deletion protection on the RDS instance.

Question 5

A company runs a containerized application on Amazon EKS. The application must be highly available across multiple Availability Zones and must automatically recover from node failures. Which THREE steps should be taken?

Accepted Answer

Use Pod Disruption Budgets to ensure a minimum number of pods are available during voluntary disruptions.. Deploy worker nodes across multiple AZs ensures node diversity. Use Pod Disruption Budgets to maintain minimum pod availability. Configure cluster auto scaling to replace failed nodes.

Answer

Deploy worker nodes in a single Availability Zone to reduce cross-AZ data transfer costs.

Answer

Use a single large instance type for all worker nodes to simplify management.

Question 6

A company wants to ensure that its Amazon S3 bucket is resilient to accidental deletion of objects. Which TWO actions should be taken?

Accepted Answer

Enable MFA Delete on the bucket.. Enable Versioning to keep multiple versions of objects, and enable MFA Delete to require multi-factor authentication for permanent deletions.

Answer

Enable S3 Object Lock.

Answer

Enable S3 Transfer Acceleration.

Answer

Configure a lifecycle policy to expire objects after 30 days.

Question 7

Refer to the exhibit. An IAM policy is attached to an IAM role used by an EC2 instance. The instance is part of an Auto Scaling group. During a scale-in event, the instance fails to stop itself. What is the MOST likely cause?

Accepted Answer

The policy does not allow ec2:TerminateInstances.. The policy allows StopInstances but does not allow ec2:TerminateInstances, which is required for Auto Scaling to terminate instances during scale-in.

Answer

The policy allows ec2:StopInstances but not ec2:StartInstances.

Answer

The policy does not allow ec2:DescribeInstanceStatus.

Answer

The policy does not allow ec2:ModifyInstanceAttribute.

Question 8

A company runs a high-traffic web application on a fleet of EC2 instances behind an Application Load Balancer (ALB) with Auto Scaling. The application uses an Amazon RDS for PostgreSQL database. Recently, during a traffic spike, the application became unresponsive. Investigation revealed that the database CPU utilization reached 100%, causing queries to timeout. The Auto Scaling group added more EC2 instances, which only increased the load on the database. The DevOps team needs to implement a solution that prevents the database from being overwhelmed during traffic spikes while maintaining application availability. The solution must be cost-effective and require minimal changes to the application code. Which solution should the DevOps team implement?

Accepted Answer

Use Amazon RDS Proxy between the application and the database to pool and reuse connections.. RDS Proxy manages database connections efficiently, reducing the number of connections and CPU overhead. It also provides connection pooling, which helps handle spikes without overwhelming the database.

Answer

Implement read replicas for the RDS database and modify the application to use read replicas for read queries.

Answer

Increase the instance size of the RDS database to a larger instance type to handle more connections.

Answer

Configure Auto Scaling to launch EC2 instances based on a custom metric that tracks database CPU utilization, and throttle the number of instances.

Question 9

A company hosts a static website on Amazon S3 with a CloudFront distribution. The website is critical for business operations and must be available even if the primary AWS Region fails. Currently, the S3 bucket is in us-east-1, and CloudFront uses that bucket as the origin. The company has a secondary bucket in us-west-2 with a replica of the data. The company wants to use CloudFront to automatically fail over to the secondary bucket if the primary becomes unavailable. The DevOps engineer needs to implement a solution that requires minimal operational overhead. What should the engineer do?

Accepted Answer

Configure CloudFront Origin Failover by adding both buckets as origins, with the primary in us-east-1 and secondary in us-west-2.. CloudFront Origin Failover allows you to set up a primary and secondary origin. If the primary returns an error (e.g., 503), CloudFront automatically routes requests to the secondary origin.

Answer

Use an Application Load Balancer in front of both S3 buckets and point CloudFront to the ALB.

Answer

Create a second CloudFront distribution pointing to the secondary bucket and use Route 53 failover routing between the two distributions.

Answer

Modify the application to switch the CloudFront origin URL using Lambda@Edge when health checks fail.

Question 10

A company uses AWS CloudFormation to deploy infrastructure. During a recent deployment, the stack failed to create an Amazon RDS DB instance because of a parameter validation error. The DevOps engineer fixed the parameter and wants to resume the stack creation without recreating the resources that were already successfully created. The stack template is parameterized and uses nested stacks. What is the MOST efficient way to resume the stack creation?

Accepted Answer

Use the CloudFormation stack update operation with the corrected parameter.. CloudFormation stack updates can be used to fix the issue. By updating the stack with the corrected parameters, CloudFormation will only modify the failed resource and not recreate already created resources.

Answer

Manually create the RDS instance with the corrected parameter and update the stack to import it.

Answer

Delete the entire stack and redeploy with the corrected parameter.

Answer

Use the 'ContinueUpdateRollback' feature to rollback the failed stack and then redeploy.

Question 11

A company runs a microservices application on Amazon ECS with Fargate. The application uses an Application Load Balancer (ALB) to route traffic to services. Each service has a required number of tasks for capacity. The company recently experienced a prolonged outage when a bug caused all tasks of the critical 'payment' service to crash simultaneously. The DevOps team needs to implement a deployment strategy that reduces the risk of a full service outage during updates. The strategy must also allow for quick rollback if a deployment fails. Which deployment strategy should the team implement?

Accepted Answer

Implement blue/green deployment using ECS with target tracking alarms to automate traffic shifting.. Blue/green deployment with target tracking allows you to gradually shift traffic to the new version while monitoring. If issues arise, you can instantly rollback by switching traffic back to the old version.

Answer

Implement a rolling update with a fixed number of tasks to replace at a time.

Answer

Use a canary deployment by creating a new service with a small number of tasks, test, then shift all traffic.

Answer

Deploy changes during maintenance windows with manual approval steps.

Question 12

A media company runs a video processing pipeline on AWS. Raw videos are uploaded to an S3 bucket, which triggers a Lambda function to start an AWS Batch job for transcoding. The Batch job reads the source video from S3, processes it, and writes the output to another S3 bucket. Recently, the company has seen an increase in processing failures. Investigation shows that the Batch jobs are being terminated with a 'TIMEOUT' status after running for exactly 30 minutes. The video files are large, and some jobs legitimately take up to 45 minutes. The Batch job definition has a 'timeout' setting configured. Which action should be taken to resolve this issue?

Accepted Answer

Modify the Batch job definition to increase the 'timeout' value to 3600 seconds (60 minutes).. The timeout configured in the job definition is causing jobs that exceed 30 minutes to be terminated. Increasing the timeout to 60 minutes allows longer-running jobs to complete.

Answer

Increase the S3 bucket lifecycle policy to retain videos longer.

Answer

Increase the Lambda function timeout to 60 minutes.

Answer

Change the Batch job queue to a different compute environment.

Question 13

A financial services company runs a critical application on Amazon ECS with Fargate launch type. The application has strict availability requirements and must survive an Availability Zone failure. The ECS service is configured with a desired count of 4 tasks, spread across two Availability Zones using a spread strategy. The service is fronted by an Application Load Balancer. During a recent AZ outage, one AZ became completely unavailable, but the application continued to serve traffic. However, after the AZ recovered, the ECS service did not automatically place new tasks in the recovered AZ to restore the desired count. The service remains with only 2 tasks in the remaining AZ. What is the most likely cause and solution?

Accepted Answer

The ECS service does not automatically replace tasks in a recovered AZ because the spread strategy is static. Manually update the service (e.g., force new deployment) to trigger rebalancing.. The ECS service uses a spread strategy, which maintains balance across AZs. When an AZ is unhealthy, ECS does not place tasks there. After recovery, the service may not automatically rebalance because the spread strategy is not proactive; it only ensures placement of new tasks. To force rebalancing, one can update the service (e.g., change desired count, then change back).

Answer

The Application Load Balancer is not health-checking the recovered AZ. Configure cross-zone load balancing.

Answer

The ECS service uses a spread strategy that does not automatically rebalance after an AZ recovers. Update the service to use a 'rebalance' strategy.

Answer

The ECS service is configured with a minimum healthy percent of 50%, which prevents replacement. Lower the minimum healthy percent to 0%.

Question 14

A startup runs a web application on EC2 instances behind an Application Load Balancer. They want to improve resilience by distributing instances across multiple Availability Zones. Currently, all instances are in us-east-1a. They create a launch template and an Auto Scaling group with a desired capacity of 2. They configure the Auto Scaling group to use two subnets: one in us-east-1a and one in us-east-1b. However, after updating, all instances remain in us-east-1a. What is the most likely reason?

Accepted Answer

The Auto Scaling group's subnet configuration was not updated to include the new subnet.. Auto Scaling group distributes instances across subnets specified. If only one subnet is used, it may be because the launch template specifies only one subnet or the Auto Scaling group's subnets were not updated. The most common cause is that the Auto Scaling group's subnet list still contains only the original subnet.

Answer

The instance type is not available in us-east-1b.

Answer

The new subnet in us-east-1b has no route to the internet.

Answer

The launch template specifies a single subnet in us-east-1a.

Question 15

A company runs a multi-tier web application on AWS. The application consists of an Application Load Balancer, EC2 instances in an Auto Scaling group, and an Amazon RDS Multi-AZ DB instance. The application experiences intermittent failures when the RDS primary instance fails over to the standby. The engineer needs to ensure that the application handles failover gracefully without manual intervention.

Accepted Answer

Use Amazon RDS Proxy to pool and reuse database connections, which reduces connection churn during failover.. Using a proxy like ProxySQL or configuring the application to use the RDS endpoint (which automatically points to the current primary) helps handle failover. Additionally, enabling RDS connection pooling or using Lambda to update the application can help, but the simplest is to use the instance endpoint with a retry mechanism.

Answer

Modify the application to use DNS caching with a TTL of 300 seconds to avoid stale DNS records.

Answer

Configure the Application Load Balancer to perform health checks on the RDS instance.

Answer

Enable Multi-AZ on the Auto Scaling group to ensure EC2 instances are in multiple AZs.