DOP-C02 Resilient Cloud Solutions Practice Test 8 — 15 Questions

Question 1

A company runs a critical batch processing workload on Amazon EMR that must complete within a 2-hour window each night. The workload is fault-tolerant but must be resilient to instance failures. Currently, the EMR cluster uses instance fleets with Spot Instances. Recently, Spot Instance interruptions caused the cluster to take over 3 hours to complete. Which change will MOST effectively ensure the workload completes within the 2-hour window despite Spot interruptions?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Use a mixed instances policy that includes multiple instance types across different Availability Zones.. A mixed instances policy across multiple Availability Zones increases the diversity of Spot capacity pools. When one instance type or zone experiences interruptions, the cluster can fall back to other pools, reducing the likelihood of prolonged delays. This approach directly addresses Spot interruption risk without sacrificing cost efficiency, as On-Demand instances would.

Answer

Increase the number of core nodes to 20 to improve parallelism.

Answer

Switch to using On-Demand instances for all nodes.

Answer

Configure the cluster to terminate idle nodes after 5 minutes to reduce costs.

Question 2

A company uses Amazon Route 53 for DNS and wants to ensure high availability for a web application hosted on two EC2 instances in different Availability Zones. The application uses an Application Load Balancer. What is the simplest way to achieve resilience if one Availability Zone becomes unavailable?

Accepted Answer

Place the instances in different Availability Zones behind the ALB.. Placing EC2 instances in different Availability Zones behind an Application Load Balancer (ALB) is the simplest and most effective way to achieve high availability. The ALB automatically distributes traffic across healthy targets in multiple AZs, and if one AZ becomes unavailable, the ALB stops routing requests to instances in that AZ, ensuring continued service from the remaining AZ.

Answer

Launch both instances in the same Availability Zone.

Answer

Configure Route 53 latency-based routing to each instance.

Answer

Configure Route 53 failover routing with health checks pointing to each instance.

Question 3

A company is deploying a stateful application on Amazon EKS. The application requires persistent storage that can be reattached to a new pod if the original pod fails. The cluster spans multiple Availability Zones. Which storage solution provides the BEST resilience and meets these requirements?

Accepted Answer

Amazon EFS file system.. Amazon EFS provides a fully managed, regional NFS file system that can be mounted concurrently by multiple pods across different Availability Zones. It is designed for high availability and durability, automatically replicating data across multiple AZs, and supports automatic reattachment to a new pod if the original pod fails, making it the best choice for stateful applications requiring resilient, shared persistent storage on Amazon EKS.

Answer

Amazon S3 bucket with a mountpoint.

Answer

Amazon EBS with gp3 volume type.

Answer

EC2 instance store volumes.

Question 4

A company runs a critical application on AWS Lambda that processes messages from an Amazon SQS queue. The application must be resilient to downstream service failures. The team notices that when the downstream service is unhealthy, messages are repeatedly retried and eventually sent to the dead-letter queue (DLQ) before the service recovers. What design change would improve resilience by allowing automatic retries after the downstream service recovers?

Accepted Answer

Configure the SQS queue with a large visibility timeout (e.g., 6 hours) and use a redrive policy only after a high number of receives. Keep the messages in the queue and retry when the downstream service becomes healthy.. Increasing the visibility timeout to a long duration (e.g., 6 hours) prevents messages from being repeatedly retried and sent to the DLQ while the downstream service is unhealthy. Instead, messages remain in the SQS queue and become visible again only after the visibility timeout expires, allowing automatic retries once the downstream service recovers. This approach avoids premature DLQ delivery and leverages SQS's built-in redrive policy based on maxReceiveCount.

Answer

Reduce the maxReceiveCount to 1 so that messages are sent to DLQ immediately, then reprocess them from DLQ later.

Answer

Increase the message retention period to 14 days and use a DLQ with high retention.

Answer

Use Amazon SNS to fan out messages to multiple SQS queues, each with different retry policies.

Question 5

A company is designing a resilient architecture for a web application using AWS Global Accelerator and two Application Load Balancers in different AWS Regions. The application is stateless and uses a global DynamoDB table for data. What is the primary benefit of using Global Accelerator in this architecture?

Accepted Answer

It provides static IP addresses and automatically routes traffic to the closest healthy ALB, improving availability and performance.. Global Accelerator provides static IP addresses and directs traffic to the nearest healthy endpoint, improving resilience and performance. Option A is wrong because Global Accelerator does not cache content. Option C is wrong because DNS routing is not the primary benefit; Global Accelerator uses anycast. Option D is wrong because Global Accelerator does not replace ALB; it works with ALBs.

Answer

It replaces the need for an Application Load Balancer.

Answer

It provides DNS-based failover between Regions.

Answer

It caches static content at AWS edge locations.

Question 6

A company runs a containerized application on Amazon ECS with Fargate. The application experiences intermittent failures due to resource exhaustion. The company wants to improve resilience by automatically replacing unhealthy tasks and scaling based on demand. Which TWO actions should the company take? (Choose TWO.)

Accepted Answer

Configure ECS service auto scaling with a target tracking policy based on CPU utilization.. ECS service auto scaling with a target tracking policy based on CPU utilization automatically adjusts the desired count of tasks to match demand, preventing resource exhaustion by scaling out when CPU is high and scaling in when low. This directly addresses the intermittent failures caused by resource exhaustion by ensuring sufficient task capacity during load spikes.

Answer

Enable cluster auto scaling to add more Fargate capacity.

Answer

Use an Auto Scaling group to manage the number of tasks.

Answer

Define a health check command in the task definition to restart unhealthy containers.

Question 7

A company is designing a disaster recovery plan for a MySQL database running on Amazon RDS. The database is critical and must have an RPO of 5 minutes and an RTO of 1 hour. The primary Region is us-east-1, and the DR Region is us-west-2. Which TWO steps should the company take to meet these requirements? (Choose TWO.)

Accepted Answer

Create a cross-Region read replica in us-west-2.. A cross-Region read replica in us-west-2 provides a near-real-time copy of the primary database, with replication lag typically measured in seconds, easily meeting the 5-minute RPO. During a disaster, promoting this read replica to a standalone instance in us-west-2 can be completed in minutes, satisfying the 1-hour RTO. This approach avoids the recovery time needed to restore from a snapshot or backup.

Answer

Enable automated backups with a 5-minute backup window.

Answer

Configure cross-Region automated snapshot copy to us-west-2.

Answer

Enable Multi-AZ deployment in us-east-1.

Question 8

A DevOps engineer ran the above command and saw this output. What is the MOST likely cause of the stack creation failure?

Accepted Answer

The launch template name specified in the CloudFormation template is incorrect or does not exist.. The error message indicates that the launch template name specified in the CloudFormation template does not match any existing launch template in the account and Region. CloudFormation resolves the launch template name at stack creation time; if the name is incorrect or the template does not exist, the Auto Scaling group creation fails with a validation error. This is the most direct cause because the launch template name is a required parameter that must reference a pre-existing resource.

Answer

The key pair specified in the launch template does not exist.

Answer

The IAM role does not have permission to create the Auto Scaling group.

Answer

The AMI ID specified in the launch template is not available in this Region.

Question 9

A DevOps engineer applies this S3 bucket policy to an S3 bucket. What is the effect of this policy?

Accepted Answer

All objects uploaded must use server-side encryption with Amazon S3 managed keys (SSE-S3).. The S3 bucket policy in question denies uploads unless the `x-amz-server-side-encryption` header is set to `AES256`, which is the value for SSE-S3 (Amazon S3 managed keys). This ensures that all objects uploaded to the bucket must be encrypted using server-side encryption with S3-managed keys (SSE-S3). Option C correctly identifies this requirement.

Answer

All objects uploaded must be encrypted with SSE-C.

Answer

All uploads to the bucket are blocked.

Answer

All objects uploaded must be encrypted with SSE-KMS.

Question 10

A DevOps engineer runs the above command and sees that instance i-0abcd1234efgh5678 is unhealthy with reason 'Target.Timeout'. The instance is running and the application on port 80 responds to curl from the instance itself. What is the MOST likely cause?

Accepted Answer

The security group for the instance does not allow inbound traffic from the ALB on port 80.. A Target.Timeout indicates the ALB health check request to the instance timed out. Since the application responds to curl locally, the issue is likely that the instance's security group is blocking inbound traffic from the ALB on port 80. Option A is incorrect because a high health check interval would not cause a timeout; it would just delay detection. Option B is incorrect because the web server is running (application responds locally). Option C is incorrect because a 404 status code would result in an HTTP 404, not a timeout.

Answer

The ALB health check interval is set too high.

Answer

The web server process is not running on the instance.

Answer

The health check path returns a 404 status code.

Question 11

A company is running a stateful web application on EC2 instances behind an Application Load Balancer. During a deployment, users report session timeouts. What should the DevOps engineer implement to ensure zero-downtime deployments without losing in-flight sessions?

Accepted Answer

Enable connection draining (deregistration delay) on the ALB target group and use lifecycle hooks to wait for the draining period.. Connection draining (deregistration delay) on the ALB target group allows in-flight requests to complete before instances are deregistered, and lifecycle hooks can be used to wait for the draining period before terminating instances, ensuring zero-downtime deployments without losing in-flight sessions. Option A is incorrect because updating the launch template and performing a rolling update does not inherently handle in-flight sessions; session stickiness would still cause timeouts if instances are terminated abruptly. Option B is incorrect because using a lifecycle hook that waits for instance termination without connection draining does not ensure that existing sessions are completed. Option D is incorrect because increasing health check intervals and unhealthy thresholds only delays the detection of unhealthy instances but does not prevent session loss during deployments.

Answer

Update the Auto Scaling group's launch template to use a new AMI and perform a rolling update.

Answer

Use an Auto Scaling group with a lifecycle hook that waits for instance termination.

Answer

Increase the health check interval and unhealthy threshold on the ALB target group.

Question 12

A financial services company runs a multi-region application on AWS. They need to ensure that if one AWS Region becomes unavailable, traffic is automatically rerouted to another region with no manual intervention. The application uses an Application Load Balancer in each region. What is the MOST resilient approach to meet this requirement?

Accepted Answer

Use AWS Global Accelerator with endpoint groups in each region and health checks.. AWS Global Accelerator uses anycast static IP addresses and directs traffic to optimal endpoints over the AWS global network. By configuring endpoint groups in each region with health checks, if a region becomes unhealthy, Global Accelerator automatically reroutes traffic to healthy endpoints in another region within seconds, providing the fastest failover without relying on DNS caching. Option A is less resilient because CloudFront origin failover introduces potential caching delays and is designed primarily for HTTP/HTTPS content. Option B is less resilient because Route 53 failover routing relies on DNS, which can be subject to client-side caching and slower propagation. Option C is less resilient because latency-based routing does not automatically failover on health; it would need to be combined with health checks and failover routing, and still suffers from DNS caching issues. Therefore, Global Accelerator offers the most resilient solution for automatic multi-region failover without manual intervention.

Answer

Use Amazon CloudFront with origins in each region and configure origin failover.

Answer

Use a Network Load Balancer in each region and configure Route 53 with failover routing.

Answer

Use Route 53 with latency-based routing and health checks on the ALB endpoints.

Question 13

A DevOps engineer is designing a disaster recovery plan for a critical database. The RTO is 15 minutes and RPO is 1 minute. Which solution meets these requirements?

Accepted Answer

Use Amazon RDS Multi-AZ with automatic failover.. Amazon RDS Multi-AZ provides synchronous replication across Availability Zones with automatic failover, achieving an RTO of typically 1–2 minutes and an RPO of seconds, well within the 15-minute RTO and 1-minute RPO requirements. Option B is wrong because cross-Region read replicas use asynchronous replication, leading to an RPO that can exceed 1 minute due to replication lag. Option C is wrong because automated snapshots have a minimum frequency of 5 minutes and restoring a snapshot takes significantly longer than 15 minutes, failing both RTO and RPO. Option D is wrong because a self-managed replication script on EC2 is complex, error-prone, and unlikely to guarantee the required RPO and RTO.

Answer

Use Amazon RDS with cross-Region read replicas and promote one during failover.

Answer

Schedule automated snapshots every 1 minute and restore in the same AZ.

Answer

Deploy a standby EC2 instance with a self-managed replication script.

Question 14

An e-commerce platform uses Amazon DynamoDB as its primary database. The platform experiences occasional read throttling during flash sales. The operations team needs to ensure that read traffic is handled without errors, while keeping costs low. What should a DevOps engineer recommend?

Accepted Answer

Enable DynamoDB Accelerator (DAX) to cache frequently read data.. DynamoDB Accelerator (DAX) provides an in-memory cache that reduces read load on the database, improving performance and reducing throttling. Option B is wrong because increasing read capacity units increases cost without optimization. Option C is wrong because DynamoDB Streams is for change data capture, not caching. Option D is wrong because Global Tables is for multi-region replication, not read scaling.

Answer

Increase the read capacity units for the table during flash sale events.

Answer

Use DynamoDB Streams to replicate reads to a separate table.

Answer

Implement Global Tables to distribute read traffic across multiple regions.

Question 15

A DevOps engineer is designing a highly available web application using Amazon Route 53. The application is deployed in two AWS Regions. The engineer wants to route traffic to the nearest healthy endpoint. Which routing policy should be used?

Accepted Answer

Latency routing. Latency-based routing (Option D) is the correct choice because it directs traffic to the AWS Region that provides the lowest latency for the end user, effectively routing to the nearest healthy endpoint. Failover routing (Option A) is designed for active-passive failover scenarios, not for routing based on proximity. Weighted routing (Option B) distributes traffic across endpoints based on assigned weights, not latency. Geolocation routing (Option C) routes based on the geographic location of the user, which may not correspond to the nearest healthy endpoint in terms of network latency.

Answer

Failover routing

Answer

Weighted routing

Answer

Geolocation routing