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

Question 1

A company is using Amazon S3 to store critical data. The company requires that all versions of objects be retained, including deleted objects, to meet compliance requirements. Which S3 feature should be enabled?

Accepted Answer

S3 Versioning. Option A is correct because S3 Versioning keeps all versions of objects, including deleted ones (marked with delete markers). Option B is wrong because MFA Delete adds an extra layer of security but does not retain all versions. Option C is wrong because S3 Object Lock prevents deletion but requires versioning to be enabled; however, versioning itself is the feature that retains all versions. Option D is wrong because lifecycle policies can transition or expire objects, not retain all versions.

Answer

S3 Object Lock

Answer

S3 Lifecycle policies

Answer

MFA Delete

Question 2

A company has a production environment that uses Amazon Route 53 for DNS and an Application Load Balancer (ALB) to distribute traffic to EC2 instances. The company wants to implement a disaster recovery plan that automatically fails over to a secondary region in case the primary region becomes unavailable. Which configuration should be used?

Accepted Answer

Use Route 53 failover routing policy with primary and secondary records and health checks.. Option B is correct because Route 53 failover routing policy with health checks on the ALB endpoint can automatically route traffic to a secondary endpoint when the primary is unhealthy. Option A is wrong because weighted routing distributes traffic based on weights, not failover. Option C is wrong because latency routing routes based on latency, not automatic failover. Option D is wrong because geolocation routing routes based on geographic location, not failover.

Answer

Use Route 53 weighted routing policy with equal weights for both regions.

Answer

Use Route 53 geolocation routing policy to route users based on their location.

Answer

Use Route 53 latency routing policy to route to the region with lowest latency.

Question 3

A company runs a critical microservice on Amazon ECS with AWS Fargate. The service must be highly available across multiple Availability Zones. The DevOps engineer configured the service with a desired count of 4 tasks spread across 2 Availability Zones. During a deployment, a new task fails to start due to a missing environment variable. The deployment fails, but the old tasks continue to run. What is the most likely cause of the deployment failure and how can the engineer ensure future deployments are resilient?

Accepted Answer

The deployment failed because the ECS service did not have the deployment circuit breaker enabled. Enable the circuit breaker with rollback.. The deployment failed because the new task could not start due to a missing environment variable, and the ECS service did not have the deployment circuit breaker enabled. Without the circuit breaker, ECS continues to attempt the deployment indefinitely or until a timeout, but it does not automatically roll back to the previous stable task set. Enabling the deployment circuit breaker with rollback ensures that if a specified number of tasks fail to start (e.g., due to health checks or runtime errors), ECS automatically rolls back to the last successful deployment, maintaining service availability.

Answer

The deployment failed because the ECS service was using the rolling update deployment controller. Change to blue/green deployment.

Answer

The deployment failed because the desired count was too low. Increase the desired count to 6.

Answer

The deployment failed because the health check grace period was too short. Increase the grace period.

Question 4

A company uses Amazon DynamoDB as the database for a mobile application. The application requires single-digit millisecond read and write latency and must be resilient to the failure of an entire AWS Region. Which DynamoDB feature should the company use?

Accepted Answer

DynamoDB global tables. DynamoDB global tables provide multi-Region, multi-active replication, ensuring the application can withstand an entire AWS Region failure while maintaining single-digit millisecond read and write latency in each Region. This is achieved through DynamoDB Streams and a last-writer-wins conflict resolution mechanism, making it the correct choice for cross-Region resilience.

Answer

DynamoDB point-in-time recovery (PITR)

Answer

DynamoDB Accelerator (DAX)

Answer

DynamoDB on-demand capacity mode

Question 5

A company runs a web application on AWS that uses Amazon SQS to decouple the frontend from the backend processing. The application experiences sudden spikes in traffic, causing the SQS queue to accumulate a large number of messages. The backend workers are unable to process messages fast enough, leading to increased latency. What solution can the company implement to improve the resilience and scalability of the backend?

Accepted Answer

Configure an Auto Scaling group for the backend workers with a scaling policy based on the SQS queue depth.. Option D is correct because configuring an Auto Scaling group for the backend workers with a scaling policy based on the SQS queue depth (ApproximateNumberOfMessagesVisible) directly addresses the sudden traffic spikes. This approach dynamically adds more worker instances when the queue depth increases, improving processing throughput and reducing latency. It ensures the backend scales in response to demand, enhancing both resilience and scalability.

Answer

Reduce the receive message wait time (long polling) to poll the queue more frequently.

Answer

Increase the visibility timeout of the SQS queue to allow more time for processing.

Answer

Use an SQS FIFO queue instead of a standard queue to ensure ordered processing.

Question 6

A company is implementing a disaster recovery strategy for its Amazon Aurora MySQL database. The primary database is in us-west-2. The company requires an RPO of less than 1 minute and an RTO of less than 5 minutes. Which solution meets these requirements?

Accepted Answer

Use Amazon Aurora Global Database with a secondary Region cluster.. Amazon Aurora Global Database is designed for low-latency cross-Region replication with a typical RPO of 1 second and RTO of 1 minute or less, meeting the <1 minute RPO and <5 minute RTO requirements. It uses a dedicated storage-level replication channel that keeps the secondary cluster fully synchronized without impacting primary performance, and failover involves promoting the secondary cluster to primary in under a minute.

Answer

Create a cross-Region read replica in the secondary Region and promote it during failover.

Answer

Use automated backups and restore to a new DB instance in the secondary Region.

Answer

Take manual snapshots of the DB instance and copy them to the secondary Region every hour.

Question 7

A company is designing a highly available architecture for a web application that uses Amazon EC2 instances. The application must be resilient to the failure of a single instance and a single Availability Zone. Which TWO actions should the company take? (Choose TWO.)

Accepted Answer

Use an Auto Scaling group with a minimum of two instances spread across two Availability Zones.. Option A is correct because an Auto Scaling group with a minimum of two instances spread across two Availability Zones ensures that if one instance or one entire AZ fails, the remaining instance(s) in the other AZ can continue serving traffic, and Auto Scaling will automatically launch a replacement instance in the healthy AZ to restore the desired count. Option B is correct because distributing EC2 instances across at least two Availability Zones is the fundamental requirement for AZ-level resilience, as it eliminates a single point of failure at the AZ boundary.

Answer

Place all EC2 instances in a single Availability Zone and use a Network Load Balancer.

Answer

Use a single Application Load Balancer in one Availability Zone.

Answer

Use a single large EC2 instance in one Availability Zone.

Question 8

A company is using AWS CloudFormation to deploy a critical application stack. The company wants to ensure that the stack can be recovered quickly in case of a failure. Which THREE strategies should the company implement? (Choose THREE.)

Accepted Answer

Use StackSets to deploy the stack across multiple Regions.. Option B is correct because AWS CloudFormation StackSets allow you to deploy stacks across multiple AWS Regions and accounts from a single template, enabling multi-Region disaster recovery. By deploying the critical application stack in multiple Regions, you can quickly fail over to a secondary Region if the primary fails, meeting the requirement for rapid recovery.

Answer

Disable rollback on stack creation failure to preserve resources for debugging.

Answer

Define the entire application in a single CloudFormation template.

Question 9

A company is designing a disaster recovery plan for an Amazon S3 data lake. The data lake stores sensitive data that must be replicated to a secondary Region with an RPO of 15 minutes. Which THREE actions should the company take? (Choose THREE.)

Accepted Answer

Enable S3 Versioning on both the source and destination buckets.. Option A is correct because enabling S3 Versioning on both the source and destination buckets is a prerequisite for S3 Replication. Without versioning, replication cannot track object versions, which is essential for meeting the 15-minute RPO with consistency guarantees.

Answer

Configure S3 Event Notifications to trigger a Lambda function that copies objects to the secondary Region.

Answer

Enable S3 Transfer Acceleration on the source bucket.

Question 10

Refer to the exhibit. A DevOps engineer applies the IAM policy shown to an S3 bucket to enforce server-side encryption. However, users report that some uploads succeed without encryption. What is the most likely reason?

Accepted Answer

The policy only allows the action but does not deny actions that do not meet the condition.. Option B is correct because the IAM policy only allows the s3:PutObject action when the encryption condition is met, but it does not include an explicit Deny statement to block uploads that do not satisfy the condition. In IAM, an Allow statement with a condition does not automatically deny requests that fail the condition; it simply does not apply the Allow. If there is another policy (e.g., a bucket policy or an identity-based policy) that grants s3:PutObject without the encryption condition, or if the default S3 behavior permits unencrypted uploads (since S3 does not require encryption by default), then unencrypted uploads can still succeed. To enforce encryption, you must add a Deny statement with a condition like `StringNotEquals` on `s3:x-amz-server-side-encryption` to explicitly reject requests that lack the required encryption header.

Answer

The policy uses StringEquals instead of StringNotEquals.

Answer

The resource ARN is incorrect; it should be the bucket ARN.

Answer

The action should be s3:PutEncryptedObject instead of s3:PutObject.

Question 11

Refer to the exhibit. A DevOps engineer applies the IAM policy shown to an S3 bucket to enforce server-side encryption. However, users report that some uploads succeed without encryption. What is the most likely reason?

Accepted Answer

The policy only allows the action but does not deny actions that do not meet the condition.. Option B is correct because the IAM policy shown only allows the s3:PutObject action when the encryption condition is met, but it does not include a Deny statement to explicitly block uploads that do not satisfy the condition. In AWS IAM, an Allow statement alone does not prevent actions that fail the condition; it simply grants permission when the condition is true. Without a corresponding Deny, users with other permissions (e.g., from a broader policy) can still upload objects without encryption, as the Allow does not override other effective allows.

Answer

The resource ARN is incorrect; it should be the bucket ARN.

Answer

The action should be s3:PutEncryptedObject instead of s3:PutObject.

Answer

The policy uses StringEquals instead of StringNotEquals.

Question 12

Refer to the exhibit. A DevOps engineer runs the describe-target-health command and receives the output shown. The ALB target group has two instances. One instance is healthy, and the other is unhealthy with a 502 error. What is the most likely cause of the 502 error?

Accepted Answer

The application running on the instance is not responding correctly or has crashed.. Option D is correct because a 502 Bad Gateway error from an ALB indicates that the target (EC2 instance) has closed the connection or the application is not responding properly. Common causes include the web server or application crashing, or the target not being able to handle the request. Option A is wrong because security group rules would cause connection timeouts (504) or refused connections, not 502. Option B is wrong because a missing route table would cause network unreachability, not a 502. Option C is wrong because the health check path returning a 404 would result in a 404, not a 502.

Answer

The security group for the instance does not allow inbound traffic on port 80 from the ALB.

Answer

The instance's route table does not have a route to the internet gateway.

Answer

The health check path is configured to return a 404 status code.

Question 13

A company runs a stateless web application on EC2 instances behind an Application Load Balancer. To improve resilience, which configuration should be used for the EC2 instances?

Accepted Answer

Use multiple EC2 instances across two or more Availability Zones. D is correct because deploying multiple EC2 instances across two or more Availability Zones (AZs) ensures high availability and fault tolerance. If one AZ fails, the Application Load Balancer (ALB) automatically routes traffic to healthy instances in other AZs, maintaining service continuity. This aligns with the AWS Well-Architected Framework's resilience best practices for stateless applications.

Answer

Use one EC2 instance with a larger instance type

Answer

Use a single, large EC2 instance in one Availability Zone

Answer

Use multiple EC2 instances in one Availability Zone with health checks disabled

Question 14

A company is designing a disaster recovery strategy for a critical application that requires a Recovery Time Objective (RTO) of 15 minutes and a Recovery Point Objective (RPO) of 1 hour. The application runs on EC2 with data stored in Amazon RDS Multi-AZ. Which approach meets these requirements?

Accepted Answer

Use a pilot light strategy with RDS cross-Region read replicas and automated backups. Option A is correct because a pilot light strategy with RDS cross-Region read replicas and automated backups meets the RTO of 15 minutes and RPO of 1 hour. The cross-Region read replica provides near-synchronous replication with an RPO typically under 5 seconds, and automated backups enable point-in-time recovery within the 1-hour RPO. The pilot light approach allows rapid promotion of the replica to a primary instance, achieving the 15-minute RTO by keeping minimal core services running in the DR Region.

Answer

Use backup and restore with daily snapshots to another Region

Answer

Use a warm standby with a scaled-down production environment in another Region

Answer

Use a Multi-AZ deployment in the same Region for DR

Question 15

A company runs a critical application on EC2 instances in an Auto Scaling group across three Availability Zones. The application uses an Amazon RDS Multi-AZ DB instance. During a recent incident, one Availability Zone experienced a complete failure. The application remained available, but performance degraded significantly. What is the most likely cause of the degradation?

Accepted Answer

The Auto Scaling group was configured to span only two Availability Zones, and the failed AZ contained a majority of the running instances. Option C is correct because if the Auto Scaling group is configured to span only two Availability Zones, the failure of one AZ would result in a disproportionate loss of capacity. Since the failed AZ contained a majority of the running instances, the remaining instances in the surviving AZ would be overloaded, causing significant performance degradation. The application remained available because the surviving instances and the Multi-AZ RDS instance continued to operate, but the reduced compute capacity led to degraded performance.

Answer

The Route 53 health checks failed and directed traffic to another Region, increasing latency

Answer

The RDS DB instance failed over to a read replica in a different Region

Answer

The EBS volumes in the failed AZ were not available, causing data loss