DOP-C02 Practice Exam 57 — 20 Questions

Question 1

A company uses an NLB to distribute traffic to a fleet of EC2 instances in a single Availability Zone. During a recent AWS outage in that zone, the application became completely unavailable. The company wants to achieve high availability without rearchitecting the application. Which change is MOST appropriate?

Accepted Answer

Launch EC2 instances in a second Availability Zone and register them with the NLB target group. Option D is correct because NLB automatically routes traffic to healthy targets across Availability Zones when targets are registered. Option A is wrong because ALB is not required; NLB can handle multi-AZ. Option B is wrong because instance type does not affect availability. Option C is wrong because it does not address zone failure.

Answer

Use a larger instance type and enable detailed CloudWatch monitoring

Answer

Replace the NLB with an Application Load Balancer and enable cross-zone load balancing

Answer

Create an Auto Scaling group with a scheduled scaling policy to add instances during peak hours

Question 2

A company runs a containerized application on Amazon ECS with Fargate. The application needs to store session state. Which service provides the MOST resilient and scalable solution?

Accepted Answer

Amazon ElastiCache for Redis. Option C is correct because ElastiCache for Redis provides a highly available, scalable, and fast in-memory data store for session state. Option A is wrong because EFS is for file storage, not session state. Option B is wrong because S3 is object storage with higher latency. Option D is wrong because local storage is ephemeral.

Answer

Amazon EFS

Answer

Ephemeral storage on the container instance

Answer

Amazon S3

Question 3

A company runs a critical web application on EC2 instances behind an Application Load Balancer. To improve resilience, they want to automatically replace failed instances. Which AWS service should they use?

Accepted Answer

Auto Scaling group with health checks. Auto Scaling automatically replaces unhealthy instances. ELB health checks integration triggers replacement. Option A is wrong because EC2 Instance Recovery only recovers on the same host. Option C is wrong because CloudFormation doesn't auto-replace. Option D is wrong because Systems Manager doesn't replace instances.

Answer

EC2 Instance Recovery

Answer

AWS Systems Manager Automation

Answer

CloudFormation Stack update

Question 4

A company uses AWS CodePipeline to deploy a web application. The pipeline includes a deploy action that uses AWS CloudFormation to update a stack. The deployment occasionally fails because of a transient resource limit error. Which automatic retry strategy should a DevOps engineer implement?

Accepted Answer

Set the deploy action's retry count to 3 in the pipeline definition. Option B is correct because CodePipeline supports automatic retry of actions; the retry count can be set to 3. Option A is wrong because the pipeline execution itself should not be retried entirely. Option C is wrong because CloudFormation does not have a built-in retry mechanism; it fails the action. Option D is wrong because Step Functions adds complexity and cost.

Answer

Use an AWS Step Function to orchestrate the deployment with retry logic

Answer

Modify the CloudFormation stack to include a retry policy

Answer

Configure the pipeline to retry the entire pipeline execution on failure

Question 5

A company has a critical application running on EC2 instances in an Auto Scaling group across two Availability Zones. The application uses an EBS volume for local caching. The company wants to ensure that if an instance fails, the cache data is not lost and the replacement instance can use it. Which solution meets this requirement?

Accepted Answer

Use Amazon EFS instead of EBS for the cache. Option D is correct because an EBS Multi-Attach volume can be attached to multiple instances in the same Availability Zone, but to persist across zones, you need to use a replication mechanism or EFS. However, the question implies a single volume for caching; the best approach is to use ElastiCache or a shared file system. Option A is wrong because snapshots are not real-time. Option B is wrong because a new volume would be empty. Option C is wrong because EBS volumes are zone-specific.

Answer

Configure the Auto Scaling group to use a launch template that attaches the same EBS volume to new instances

Answer

Take periodic EBS snapshots and create a new volume from the snapshot for the replacement instance

Answer

Use an EBS Multi-Attach volume and attach it to all instances in the Auto Scaling group

Question 6

A company runs a containerized microservices architecture on Amazon ECS with Fargate. The services communicate via an internal Application Load Balancer. Recently, a new deployment of Service A caused its health checks to fail. The DevOps engineer notices that the old tasks remain running and the service is unavailable. What configuration change would prevent this issue in future deployments?

Accepted Answer

Set the deployment minimum healthy percent to 50 and maximum percent to 100 with a health check grace period. Setting the deployment minimum healthy percent to 50 and maximum percent to 100 ensures that during a deployment, at least 50% of tasks are healthy, but if health checks fail, the deployment can roll back because the old tasks are not replaced until new tasks are healthy. Option B is wrong because it allows replacing all tasks before health checks pass. Option C is wrong because it is a deployment controller, not a configuration to prevent failure. Option D is wrong because it removes the ability to roll back.

Answer

Set the deployment circuit breaker to rollback on deployment failure and disable rollback

Answer

Change the deployment controller from ECS to CodeDeploy for blue/green deployments

Answer

Set the deployment minimum healthy percent to 0 and maximum percent to 200

Question 7

A company wants to protect its S3 bucket data from accidental deletion or overwrite. Which feature should be enabled?

Accepted Answer

Enable S3 Versioning. S3 Versioning keeps all versions, allowing recovery from deletes and overwrites. Option B is wrong because MFA Delete is an additional protection but not the primary. Option C is wrong because bucket policies control access. Option D is wrong because replication is for cross-region copies.

Answer

Enable cross-region replication

Answer

Apply a bucket policy that denies DeleteObject

Answer

Enable MFA Delete

Question 8

A DevOps team uses AWS CodePipeline to deploy a web application. The pipeline has a deploy stage that uses CodeDeploy to deploy to an Auto Scaling group. During deployment, the new instances fail health checks and the deployment rolls back. However, the rollback also fails because the old instances have been terminated. What should the team do to avoid this issue?

Accepted Answer

Use a blue/green deployment strategy in CodeDeploy to keep the old instances running until the new ones pass health checks.. Option B is correct because using a blue/green deployment with CodeDeploy allows the old instances to remain until the new ones are verified healthy. Option A is wrong because increasing the health check grace period does not help if instances are unhealthy. Option C is wrong because manual approval does not prevent the rollback failure. Option D is wrong because creating a new Auto Scaling group does not inherently solve the termination issue.

Answer

Increase the health check grace period in the Auto Scaling group.

Answer

Add a manual approval step before the deploy stage.

Answer

Configure the pipeline to deploy to a new Auto Scaling group each time.

Question 9

A company runs a stateful web application on EC2 instances behind an ALB. The application uses sticky sessions (session affinity) to maintain user sessions. During a deployment, the company wants to update the application with zero downtime and ensure that in-flight sessions are not lost. Which deployment strategy should they use?

Accepted Answer

Use a blue/green deployment: launch a new Auto Scaling group, register it with a new target group, and gradually shift traffic using weighted target groups on the ALB.. Option C is correct because a blue/green deployment with a new target group and a gradual shift of traffic using the ALB's weighted target groups allows existing sessions to complete on the old environment while new sessions go to the new one. Option A is wrong because rolling update with a fixed number of instances may cause session loss. Option B is wrong because immutable deployment without traffic shifting drops sessions. Option D is wrong because canary deployment with Lambda is not applicable to EC2.

Answer

Perform a rolling update of the Auto Scaling group with a health check grace period.

Answer

Use an immutable deployment by launching a new Auto Scaling group and then updating the ALB target group to point to the new group.

Answer

Use a canary deployment with AWS Lambda to gradually route a percentage of requests to the new version.

Question 10

A company is designing a disaster recovery strategy for its application. The application runs on EC2 instances and uses an RDS MySQL database. The RTO is 1 hour, and the RPO is 15 minutes. Which TWO approaches meet these requirements?

Accepted Answer

Use a warm standby strategy: run a scaled-down version of the application in the DR region with RDS Multi-AZ across regions.. Options A and C are correct. A pilot light with RDS cross-region replication can achieve low RPO and RTO. A warm standby with Multi-AZ in another region also meets the targets. Option B is wrong because backup and restore from snapshots may exceed RTO. Option D is wrong because Multi-Zone is not an AWS term; Multi-AZ in same region does not protect against region failure. Option E is wrong because read replicas do not provide automatic failover.

Answer

Use a read replica in the DR region and promote it on failover.

Answer

Use a Multi-Zone deployment with RDS in the same region.

Answer

Use a backup and restore strategy: take snapshots every hour and restore in the DR region on failover.

Question 11

A company wants to ensure that its application running on AWS can withstand the failure of an entire AWS Region. Which TWO strategies should the company implement?

Accepted Answer

Deploy the application in multiple AWS Regions using an active-active or active-passive pattern. B and C are correct. Multi-Region deployment provides regional isolation. Data replication ensures data availability. Option A is wrong because Multi-AZ protects only within a Region. Option D is wrong because a single CloudFront distribution with multiple origins does not guarantee regional failover. Option E is wrong because RDS read replicas are for read scaling, not disaster recovery.

Answer

Deploy the application across multiple Availability Zones in a single Region

Answer

Use a single CloudFront distribution with multiple origins in the same Region

Answer

Configure RDS read replicas in the same Region

Question 12

A company runs a critical application on EC2 instances in an Auto Scaling group. The application uses an EBS volume attached to each instance for temporary data. The company needs to ensure that if an instance fails, the data is not lost, and the new instance can resume quickly. What should they do?

Accepted Answer

Use an EBS Multi-Attach volume attached to all instances in the Auto Scaling group. Using an EBS Multi-Attach volume allows multiple instances in the same AZ to attach the same volume, providing shared access and quick recovery. Option A is wrong because EBS snapshots are point-in-time and take time to restore. Option C is wrong because EFS is a file system, not block storage, and may not be compatible with the application. Option D is wrong because instance store is ephemeral.

Answer

Store temporary data on instance store volumes instead of EBS

Answer

Use an EBS snapshot and create a new volume from the snapshot for the new instance

Answer

Migrate to Amazon EFS and mount the same file system on all instances

Question 13

A company runs a critical microservices architecture on Amazon ECS with Fargate. They want to ensure that if a task fails, it is automatically restarted, and the service remains available across multiple Availability Zones. How should they configure the ECS service?

Accepted Answer

Define an ECS service with a task definition, set desired count across multiple Availability Zones, and use Service Auto Scaling. Setting the number of tasks across multiple AZs and enabling Service Auto Scaling with task-level restart ensures resilience. The ECS service scheduler automatically restarts failed tasks. Option A is wrong because a single-AZ deployment is a single point of failure. Option B is wrong because placing all tasks in one AZ does not provide AZ resilience. Option D is wrong because a standalone task does not have automatic restart.

Answer

Place all tasks in the same Availability Zone to reduce latency

Answer

Run a standalone Fargate task and use a CloudWatch alarm to restart it

Answer

Use an EC2 launch type with a single instance to reduce complexity

Question 14

A company runs a microservices architecture on Amazon ECS with Fargate. Services communicate via an internal Application Load Balancer. Recently, one service became unavailable due to a memory leak, causing cascading failures in downstream services. What design change would MOST effectively improve resilience and limit the blast radius?

Accepted Answer

Implement circuit breaker patterns in the service discovery and client libraries to stop calling unhealthy services.. Option C is correct because circuit breakers prevent cascading failures by stopping calls to unhealthy services. Option A is wrong because increasing task memory may delay but not prevent the failure. Option B is wrong while helpful for scaling, it does not prevent requests from being sent to failing services. Option D is wrong because connection draining only manages in-flight connections during deregistration, not cascading failures.

Answer

Increase the memory limit for each ECS task to accommodate memory leaks.

Answer

Enable connection draining on the ALB to allow in-flight requests to complete.

Answer

Implement automatic scaling policies for ECS services based on memory utilization.

Question 15

A company is designing a disaster recovery plan for a critical application that uses Amazon RDS for MySQL with Multi-AZ. The RPO must be less than 1 minute and RTO less than 15 minutes. The primary Region is us-east-1. Which THREE steps should the company take to meet these requirements?

Accepted Answer

Create a cross-Region read replica of the RDS instance in the secondary Region. B, C, and E are correct. Cross-Region read replica provides near-real-time replication (low RPO) and can be promoted quickly (low RTO). Automated backups are replicated to another Region and can be restored, but RTO may exceed 15 minutes. Option A is wrong because manual snapshots cannot achieve <1 minute RPO. Option D is wrong because Multi-AZ protects within a Region only.

Answer

Take manual snapshots of the RDS instance every 30 seconds and copy them to the secondary Region

Answer

Enable Multi-AZ in the primary Region

Question 16

A company runs a web application on EC2 instances behind an Application Load Balancer. The application uses an Aurora MySQL database. Recently, the database experienced a failover, and the application started throwing connection errors. The DevOps engineer needs to make the application resilient to database failovers with minimal code changes. What should they do?

Accepted Answer

Configure the application to use the Aurora cluster endpoint for database connections. Using the Aurora cluster endpoint with a read-write endpoint that automatically points to the new writer after a failover ensures the application reconnects without code changes. Option A is wrong because the reader endpoint is for read-only. Option C is wrong because a read replica does not automatically failover. Option D is wrong because RDS proxy does not change the endpoint behavior.

Answer

Configure the application to use the Aurora reader endpoint for all queries

Answer

Create a cross-Region read replica and configure the application to retry on failure

Answer

Use Amazon RDS Proxy with IAM authentication to handle connection pooling

Question 17

A company is designing a multi-region active-active architecture for a stateless web application using Route 53 latency-based routing. The application uses an RDS MySQL database. What should be done to ensure database resilience across regions?

Accepted Answer

Create cross-region read replicas and promote to master during failover. Cross-region read replicas can be promoted to master in disaster. Option A is wrong because Aurora Global Database is better but not listed as an option; but read replica promotion is supported. Option B is wrong because Multi-AZ is single-region. Option C is wrong because RDS doesn't support synchronous cross-region replication. Option D is wrong because snapshot restore is manual and slow.

Answer

Configure automated snapshots and copy them to the secondary region

Answer

Use RDS Cross-Region Synchronous Replication

Answer

Enable Multi-AZ deployment in each region

Question 18

A company uses an Application Load Balancer (ALB) to distribute traffic to EC2 instances. The ALB is in us-east-1a and us-east-1b. They want to ensure that if one AZ fails, traffic is routed only to healthy instances in the other AZ. What configuration is necessary?

Accepted Answer

Enable cross-zone load balancing on the ALB. Cross-zone load balancing must be enabled on the ALB so that traffic can be distributed across instances in all AZs. If disabled, each AZ receives traffic only from its own subnet. Option B is wrong because health checks are already required. Option C is wrong because stickiness doesn't affect failover. Option D is wrong because enabling more AZs helps but without cross-zone balancing, traffic may not be evenly distributed.

Answer

Enable sticky sessions (session affinity)

Answer

Configure health checks on the target group

Answer

Add more subnets in additional AZs

Question 19

A company uses AWS Lambda for processing events from Amazon S3. Recently, the Lambda function started timing out after the 15-minute limit for some large files. The function downloads the entire file to /tmp before processing. What should a DevOps engineer do to resolve this issue with minimal code changes?

Accepted Answer

Use S3 Select to filter and retrieve only necessary data, reducing file size. Splitting the file into smaller parts using S3 Select allows processing within the Lambda timeout without changing the overall architecture. Option A is wrong because increasing memory does not increase timeout beyond 15 minutes. Option C is wrong because reading the file in chunks from S3 still requires processing within the Lambda timeout. Option D is wrong because moving to a different runtime does not remove the timeout limit.

Answer

Switch the Lambda runtime from Python to Node.js for faster execution

Answer

Increase the Lambda function memory to 10,240 MB to improve CPU performance

Answer

Modify the function to read the file in streaming chunks from S3

Question 20

A company wants to design a highly available and fault-tolerant architecture for a stateless web application on AWS. Which TWO actions should they take? (Choose two.)

Accepted Answer

Launch EC2 instances in at least two Availability Zones. Deploying EC2 instances in multiple Availability Zones and using an Auto Scaling group ensures fault tolerance and high availability. Option B is wrong because a single instance in one AZ is not fault-tolerant. Option D is wrong because Multi-AZ is for RDS, not for web application instances. Option E is wrong because a single ALB is sufficient; multiple ALBs are not needed.

Answer

Use a single large EC2 instance to simplify management

Answer

Deploy multiple Application Load Balancers in each AZ

Answer

Use an RDS Multi-AZ deployment for the web server fleet