DOP-C02 Resilient Cloud Solutions Practice Test 11 — 15 Questions

Question 1

A company runs a microservices architecture on Amazon ECS with Fargate. Services communicate via an internal Application Load Balancer (ALB). The operations team notices that occasional traffic spikes cause increased latency and timeouts. The team wants to improve resilience without over-provisioning. Which THREE steps should be taken? (Choose THREE.)

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

Accepted Answer

Enable ECS Service Connect for inter-service communication to manage traffic distribution.. B is correct because ECS Service Connect provides built-in traffic management for inter-service communication, including load balancing, retries, and circuit breaking. This helps distribute traffic more evenly during spikes, reducing latency and timeouts without requiring over-provisioning.

Answer

Increase the CPU and memory limits in the task definitions.

Answer

Use EC2 launch type with Spot Instances to reduce cost.

Question 2

A company runs a critical web application on AWS using an Application Load Balancer (ALB) in front of an Auto Scaling group of EC2 instances. The application experiences periodic traffic spikes. To handle these spikes, the company wants to use a combination of proactive scaling based on a predictable schedule and reactive scaling based on CPU utilization. What is the MOST resilient scaling strategy?

Accepted Answer

Use a scheduled scaling policy for the predictable spikes and a step scaling policy for CPU utilization.. It combines scheduled scaling for predictable traffic spikes with step scaling for reactive adjustments based on CPU utilization, providing both proactive and reactive resilience. Scheduled scaling adjusts capacity in advance of known events, while step scaling allows for larger, more aggressive adjustments when CPU utilization exceeds thresholds, avoiding the slower, linear response of target tracking. This dual approach ensures the application can handle spikes without over-provisioning or under-provisioning.

Answer

Use predictive scaling based on historical traffic patterns.

Answer

Use manual scaling by increasing the desired capacity before expected spikes.

Answer

Use a target tracking scaling policy based on average CPU utilization.

Question 3

A company is designing a multi-region active-active architecture for a stateless web application. The application uses a DynamoDB table as its data store. The company wants to minimize write latency and ensure that writes are accepted in any region with eventual consistency. Which DynamoDB feature should they use?

Accepted Answer

DynamoDB global tables.. DynamoDB global tables provide a fully managed, multi-region, multi-active solution that automatically replicates data across AWS Regions. This enables low-latency writes in any region with eventual consistency, meeting the requirement for an active-active architecture without custom code or additional infrastructure.

Answer

DynamoDB read replicas in each region.

Answer

Cross-region replication using AWS Lambda function.

Answer

DynamoDB Accelerator (DAX) with multi-region endpoints.

Question 4

A company runs a microservices architecture on Amazon ECS with Fargate. Services communicate via an internal Application Load Balancer (ALB). The operations team notices that occasional traffic spikes cause increased latency and timeouts. The team wants to improve resilience without over-provisioning. Which THREE steps should be taken? (Choose THREE.)

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

Accepted Answer

Use a task placement strategy that spreads tasks across Availability Zones.. The 'spread across Availability Zones' strategy explicitly distributes ECS tasks across multiple AZs, ensuring that if one AZ fails, the remaining AZs continue to run the service. This is the most resilient approach for Fargate tasks, as it leverages the AZ isolation provided by AWS to minimize the blast radius of a single-AZ failure.

Answer

Use a task placement constraint to run tasks on distinct instances.

Answer

Use a task placement strategy that uses the random algorithm.

Answer

Use a task placement strategy that uses the binpack algorithm to maximize resource utilization.

Question 5

A company is designing a disaster recovery strategy for its on-premises database to AWS using AWS Elastic Disaster Recovery (AWS DRS). The recovery time objective (RTO) is 15 minutes, and the recovery point objective (RPO) is 1 minute. Which configuration should they use?

Accepted Answer

Configure AWS DRS to continuously replicate data to a staging area in AWS, and launch instances in the target region on failover.. AWS DRS (formerly CloudEndure) provides continuous block-level replication with sub-second RPO, which meets the 1-minute RPO requirement. By replicating to a staging area and launching instances in the target region on failover, it can achieve an RTO of 15 minutes or less, as the instances are pre-configured and ready for rapid launch.

Answer

Use AWS CloudEndure Disaster Recovery (now AWS DRS) with periodic replication every hour.

Answer

Use AWS Backup to take snapshots every 5 minutes and restore in the target region.

Answer

Use RDS cross-region automated backups with a 5-minute backup window.

Question 6

A company runs a containerized application on Amazon EKS. They want to ensure that if a node fails, the pods are rescheduled on healthy nodes. Which configuration is necessary?

Accepted Answer

Configure the EKS managed node group with a health check and ensure that the Kubernetes control plane automatically reschedules pods from failed nodes.. EKS managed node groups automatically register nodes with the Kubernetes control plane, and the Kubernetes node controller (part of the kube-controller-manager) monitors node health via the NodeLifecycleController. When a node fails (e.g., due to an EC2 instance termination or health check failure), the control plane marks the node as `NotReady` and, after the default pod eviction timeout (5 minutes), evicts pods from the failed node, rescheduling them on healthy nodes. This behavior is inherent to Kubernetes and does not require additional configuration beyond using a managed node group.

Answer

Configure a pod disruption budget to prevent too many pods from being terminated simultaneously.

Answer

Use a horizontal pod autoscaler to increase the number of pods during high load.

Answer

Use a cluster autoscaler to automatically add new nodes when pods are pending.

Question 7

A company has a serverless application using AWS Lambda functions that process messages from an Amazon SQS queue. The Lambda function sometimes fails due to transient errors. The company wants to ensure that failed messages are retried and eventually processed or sent to a dead-letter queue after 3 retries. What is the correct configuration?

Accepted Answer

Configure the SQS queue's redrive policy with maxReceiveCount: 3 and a dead-letter queue.. For Lambda functions that poll an SQS queue, the retry behavior and dead-letter queue are configured on the SQS queue itself using a redrive policy. The redrive policy specifies the maxReceiveCount (e.g., 3) and the ARN of the dead-letter queue. After a message is received the specified number of times without being deleted, SQS moves it to the DLQ. This is the correct way to handle retries and DLQ for SQS-triggered Lambda.

Answer

Set the Lambda function's retry policy to Maximum retries: 3 and configure a DLQ on the Lambda function.

Answer

Set the Lambda function's DLQ to an SQS queue and configure the event source mapping to use that DLQ after 3 retries.

Answer

Create an AWS Step Functions workflow that polls the SQS queue, processes messages, and retries failures up to 3 times before moving to a DLQ.

Question 8

A company is building a multi-tier web application on AWS. The web tier runs on EC2 instances behind an ALB. The application tier runs on EC2 instances that are not publicly accessible. The database tier runs on RDS MySQL. Which design provides the HIGHEST level of resilience for the database tier?

Accepted Answer

Deploy an RDS DB instance in a Multi-AZ configuration.. Multi-AZ RDS automatically provisions and maintains a synchronous standby replica in a different Availability Zone. If the primary DB instance fails, RDS automatically fails over to the standby, providing high availability with minimal downtime. This design ensures the database tier remains resilient against AZ-level failures without manual intervention.

Answer

Deploy a single RDS DB instance in one Availability Zone.

Answer

Deploy an RDS DB instance with a cross-region read replica.

Answer

Deploy an RDS DB instance with a read replica in the same region.

Question 9

A company runs a stateful web application on EC2 instances that store session data locally. They want to migrate to a stateless architecture for better resilience. Which TWO actions should they take?

Accepted Answer

Use Amazon DynamoDB to store session data.. DynamoDB provides a fully managed, low-latency, highly available NoSQL database that is ideal for storing session state externally. By moving session data to DynamoDB, the EC2 instances become stateless, allowing any instance to handle any request without relying on local storage, which improves resilience and scalability.

Answer

Use Amazon CloudFront to cache session data at the edge.

Answer

Use Amazon S3 to store session data as objects.

Answer

Use Amazon EFS to store session data as files.

Question 10

A company runs a critical application on AWS that uses an Auto Scaling group of EC2 instances. The application must remain available even if an entire Availability Zone fails. Which THREE actions should the company take?

Accepted Answer

Configure an ALB health check to automatically replace unhealthy instances.. Configuring an ALB health check allows the Auto Scaling group to automatically detect and replace unhealthy instances. The ALB health check pings the instances at a specified interval (e.g., every 30 seconds) and marks them as unhealthy if they fail to respond. This triggers the Auto Scaling group to terminate the unhealthy instance and launch a new one, maintaining application availability even if an instance fails within a single AZ.

Answer

Use a single instance in each Availability Zone to minimize cost.

Answer

Use multiple subnets in each Availability Zone for the instances.

Question 11

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 B are correct. A warm standby with RDS Multi-AZ across regions ensures a standby database is ready and can be promoted quickly, meeting the 1-hour RTO. A pilot light with RDS cross-region automated backups provides replication with a 15-minute RPO; a small environment is running, allowing faster failover than a full pilot light. Option C is wrong because RDS read replicas do not support automatic failover; manual promotion can take longer than 1 hour. Option D is wrong because Multi-AZ in the same region does not protect against region failure. Option E is wrong because hourly snapshots meet RPO but restoring from snapshots typically exceeds the 1-hour RTO.

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 12

A company uses DynamoDB global tables with two regions. They notice that writes in one region are not replicating to the other region after a brief network partition. Which configuration will ensure replication resumes automatically?

Accepted Answer

No action needed; DynamoDB automatically resumes replication when connectivity is restored.. DynamoDB global tables use a last-writer-wins (LWW) conflict resolution mechanism and are designed to handle temporary network partitions. When connectivity is restored, DynamoDB automatically resumes replication of pending writes using its internal replication engine, which is built on DynamoDB Streams. No manual intervention is required because the service manages eventual consistency across regions.

Answer

Use DynamoDB Streams with a Lambda function to manually replicate writes.

Answer

Manually fail over the table to the other region.

Answer

Delete the replica table and recreate it.

Question 13

A company wants to ensure its RDS Multi-AZ deployment automatically fails over to a standby instance in a different Availability Zone. Which additional step is required?

Accepted Answer

No additional step; RDS Multi-AZ handles automatic failover.. Amazon RDS Multi-AZ automatically handles failover to the standby instance in a different Availability Zone without any additional configuration. When the primary DB instance becomes unavailable, RDS automatically detects the failure and flips the DNS record to point to the standby instance, typically within 60–120 seconds. No manual intervention or extra services like Route 53 health checks are required for this built-in failover mechanism.

Answer

Create an Amazon Route 53 health check to update the DNS record.

Answer

Configure a read replica in another AZ.

Answer

Deploy the standby instance in a different VPC.

Question 14

A company runs a Stateful application on EC2 that requires sticky sessions. They use an ALB with duration-based stickiness. During a deployment, they want to drain existing connections gracefully before terminating instances. Which step is necessary?

Accepted Answer

Increase the deregistration delay on the target group.. ALB target groups use a 'deregistration delay' (formerly called connection draining) to allow in-flight requests to complete before an instance is terminated. This setting is configured on the target group, not the load balancer, and it works with sticky sessions by waiting for the delay period (default 300 seconds) for existing connections to finish, even if the stickiness cookie would otherwise route new requests to the same instance. During a deployment, increasing this delay or ensuring it is set appropriately is the necessary step to gracefully drain connections.

Answer

Reduce the stickiness duration to zero.

Answer

Configure health checks to mark instances unhealthy.

Answer

Enable connection draining on the target group.

Question 15

A company wants to automate the recovery of an Amazon RDS DB instance in a different region if the primary region becomes unavailable. Which service should they use?

Accepted Answer

RDS cross-region automated backups.. RDS cross-region automated backups can be restored to a different region. Option A is incorrect because RDS Multi-AZ only provides failover within the same region. Option C is incorrect because read replicas can be promoted but require manual intervention. Option D is incorrect because RDS does not support CloudFormation for automated recovery across regions.

Answer

RDS Multi-AZ deployment.

Answer

RDS read replicas.

Answer

AWS CloudFormation custom resource.