DOP-C02 Resilient Cloud Solutions Practice Test 7 — 15 Questions

Question 1

A company's DevOps team is designing a disaster recovery plan for a critical application. The application runs on EC2 instances with an RDS MySQL database. The Recovery Time Objective (RTO) is 15 minutes, and the Recovery Point Objective (RPO) is 1 hour. Which approach BEST meets these requirements?

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

Accepted Answer

Use a multi-Region application with Route 53 latency-based routing and RDS read replicas in the DR Region.. The best approach for a multi-Region disaster recovery with RTO of 15 minutes and RPO of 1 hour. By deploying the application in multiple regions and using RDS cross-Region read replicas, data is asynchronously replicated with an RPO typically within seconds to minutes, well within 1 hour. In the event of a failure, the read replica can be promoted to a primary instance, and Route 53 routing (preferably failover routing, but latency-based routing can also redirect traffic) can shift traffic to the DR region. This failover can be completed within a few minutes, meeting the 15-minute RTO. Option A fails because daily snapshots exceed the 1-hour RPO and restore times exceed the RTO. Option C incorrectly relies on RDS Multi-AZ, which is a single-region high-availability feature and does not provide cross-region replication; thus it cannot serve as a disaster recovery solution across regions. Option D, pilot light with snapshots, has a longer RTO as it requires restoring instances from snapshots and starting them, likely exceeding 15 minutes.

Answer

Use backup and restore with daily snapshots stored in S3 and cross-Region replication.

Answer

Use a warm standby strategy with a scaled-down copy of the production environment in the DR Region, and replicate data using RDS Multi-AZ with synchronous replication.

Answer

Use a pilot light strategy with EC2 instances stopped and RDS snapshots copied to the DR Region.

Question 2

A company's application uses Amazon SQS to decouple microservices. During peak hours, the SQS queue backlog grows significantly, causing processing delays. The DevOps team wants to reduce latency without increasing costs unnecessarily. What should the team do?

Accepted Answer

Configure Auto Scaling for the consumer fleet based on the ApproximateNumberOfMessagesVisible metric.. Scaling the consumer fleet based on the ApproximateNumberOfMessagesVisible metric directly addresses the backlog by adding more processing capacity when the queue grows. This approach reduces latency dynamically without incurring unnecessary costs during off-peak hours, as it only scales up when needed. Auto Scaling with SQS metrics is a cost-effective, elastic solution for handling variable workloads.

Answer

Increase the visibility timeout to allow consumers more time to process messages.

Answer

Use an SQS queue with priority settings to process high-priority messages first.

Answer

Increase the SQS queue's throughput by requesting a quota increase.

Question 3

A company runs a microservices application on Amazon ECS with Fargate. The application includes a service that processes orders and stores them in an RDS PostgreSQL database. The company wants to ensure that the order service is resilient to AZ failures and can handle a sudden increase in order volume. Which TWO actions should the DevOps engineer take? (Choose TWO.)

Accepted Answer

Deploy the RDS instance in a Multi-AZ configuration.. Deploying the RDS instance in a Multi-AZ configuration provides automatic failover to a standby replica in a different Availability Zone, ensuring database resilience to AZ failures. Option D is correct because configuring the ECS service to run tasks in multiple Availability Zones distributes the order processing workload across AZs, improving both fault tolerance and scalability during sudden traffic spikes.

Answer

Increase the CPU and memory limits for the ECS task definition.

Answer

Place an Amazon CloudFront distribution in front of the order service.

Answer

Use RDS Proxy to manage database connections.

Question 4

A company's application uses Amazon DynamoDB as its primary data store. The application experiences occasional throttling errors during traffic spikes. The DevOps team needs to implement a solution that ensures consistent performance without manual intervention. Which TWO actions should the team take? (Choose TWO.)

Accepted Answer

Implement DynamoDB Accelerator (DAX) to cache read requests.. To handle occasional throttling during traffic spikes without manual intervention, the team should use DynamoDB Accelerator (DAX) to cache read requests, reducing read load on the table, and enable DynamoDB Auto Scaling to automatically adjust read and write capacity based on traffic patterns. DAX absorbs spikey read traffic, while Auto Scaling ensures sufficient capacity for writes and uncached reads, together providing consistent performance without manual scaling. Option E (On-Demand) also handles spikes automatically but can be costlier for predictable workloads; the combination of DAX and Auto Scaling is often more cost-effective for read-heavy applications.

Answer

Use eventually consistent reads for all queries.

Answer

Move the data to Amazon RDS with read replicas.

Answer

Switch DynamoDB to On-Demand capacity mode.

Question 5

A company runs a critical e-commerce platform on AWS. The architecture includes an Application Load Balancer (ALB) that distributes traffic to a fleet of EC2 instances in an Auto Scaling group across three Availability Zones. The instances run a Java application that connects to an Amazon RDS Multi-AZ MySQL database. The application also uses Amazon ElastiCache for Redis for session caching. The company recently experienced a severe outage where the ALB's 5xx error rate spiked to 100% for 45 minutes. The root cause was a combination of a slow-running query on the RDS primary instance and a subsequent failover that caused the application to lose connections to the database. The failover happened because the slow query caused the primary to become unresponsive, triggering a Multi-AZ failover. During the failover, the application's connection pool exhausted, and new connections failed. The application logs show a high rate of 'java.sql.SQLTimeoutException' and 'com.mysql.cj.exceptions.CJCommunicationsException'. The DevOps team needs to implement a long-term solution that minimizes the impact of similar incidents. The solution must be cost-effective and require minimal application changes. Which combination of actions should the DevOps team take?

Accepted Answer

Implement Amazon RDS Proxy to manage database connections and add read replicas to offload read traffic.. Amazon RDS Proxy is the correct solution because it efficiently manages database connection pooling, reducing the likelihood of connection exhaustion during failovers. By maintaining a warm connection pool and automatically reconnecting to the new primary after a Multi-AZ failover, RDS Proxy minimizes application-side connection timeouts and errors like SQLTimeoutException and CJCommunicationsException. Adding read replicas offloads read traffic, reducing the load on the primary and mitigating the risk of slow queries causing unresponsiveness. This combination requires minimal application changes and is cost-effective compared to scaling the primary instance.

Answer

Use an Auto Scaling policy for EC2 based on RDS connection count and implement a read replica for the primary.

Answer

Configure Multi-AZ RDS with a synchronous standby and use Amazon RDS for MySQL with enhanced monitoring.

Answer

Increase the instance size of the RDS primary and enable Performance Insights to identify slow queries.

Question 6

A company is designing a disaster recovery (DR) strategy for a stateless web application deployed on Amazon ECS with Fargate. The application is fronted by an Application Load Balancer (ALB) and uses Amazon ElastiCache for Redis for session state. The primary region is us-east-1. The DR plan requires a Recovery Point Objective (RPO) of 15 minutes and a Recovery Time Objective (RTO) of 30 minutes. Which solution meets these requirements with the LEAST operational overhead?

Accepted Answer

Deploy an ALB with a warm standby ECS service in us-west-2. Use Route 53 health checks to route traffic to the secondary region if primary fails. Use ElastiCache Global Datastore for Redis to replicate data across regions.. It uses ElastiCache Global Datastore for Redis, which provides cross-region replication with an RPO of seconds (well within 15 minutes) and automatic failover, minimizing operational overhead. The warm standby ECS service in us-west-2 with Route 53 health checks allows traffic to be redirected within the 30-minute RTO without manual intervention, as the ALB and ECS service are pre-provisioned.

Answer

Deploy an Active-Active configuration across two AWS regions using Route 53 latency routing. Use ElastiCache for Redis Global Datastore with multi-region writes.

Answer

Deploy a Pilot Light environment in us-west-2 with a scaled-down ECS service and Redis cluster. Use Route 53 DNS failover. On disaster, scale up the ECS service and promote the Redis cluster.

Answer

Use Amazon ECS with Fargate in us-east-1 only, and schedule daily snapshots of ElastiCache for Redis. In case of disaster, restore the snapshot in a new region and update DNS.

Question 7

A development team wants to ensure that their application can continue serving traffic even if an entire AWS Availability Zone (AZ) becomes unavailable. The application runs on Amazon EC2 instances in an Auto Scaling group and uses an Application Load Balancer (ALB). Which configuration should the team implement to meet this requirement?

Accepted Answer

Configure the Auto Scaling group to launch EC2 instances across multiple AZs, and ensure the ALB is enabled for cross-zone load balancing.. Deploying EC2 instances across multiple Availability Zones (AZs) ensures that if one AZ fails, the remaining AZs continue to serve traffic. Enabling cross-zone load balancing on the ALB distributes incoming requests evenly across all healthy instances in all AZs, preventing traffic from being sent only to instances in the same AZ as the client. This architecture meets the requirement for high availability and fault tolerance at the AZ level.

Answer

Use a launch template with multiple instance types to ensure diversity across the fleet.

Answer

Use a single AZ but configure EC2 Auto Scaling to replace unhealthy instances automatically.

Answer

Launch all EC2 instances in the same AZ to minimize latency, and configure the Auto Scaling group to maintain a minimum of two instances.

Question 8

A company runs a containerized microservices application on Amazon EKS. The application includes a critical service that processes real-time financial transactions. This service must be highly available and resilient to node failures. The current setup uses a Deployment with 3 replicas and a ClusterIP service. During a recent node failure, the application experienced a brief period of unavailability. Which action should the DevOps engineer take to improve resilience without changing the underlying infrastructure?

Accepted Answer

Configure a PodDisruptionBudget with a maxUnavailable of 1, and add pod anti-affinity rules to spread pods across different nodes.. A PodDisruptionBudget with maxUnavailable=1 ensures that at most one pod is unavailable during voluntary disruptions, while pod anti-affinity rules force the scheduler to distribute pods across different nodes. This combination prevents a single node failure from taking down all replicas, maintaining service availability without altering the underlying infrastructure.

Answer

Change the service type from ClusterIP to NodePort and configure an external load balancer.

Answer

Increase the number of replicas to 10 and use a node selector to schedule all pods on the largest instance type.

Answer

Enable HorizontalPodAutoscaler with a target CPU utilization of 50% to automatically scale the Deployment.

Question 9

A company is building a multi-tier web application on AWS. The application must be resilient to the failure of an entire Availability Zone. The architecture includes an Application Load Balancer (ALB), EC2 instances in an Auto Scaling group, and an Amazon RDS for MySQL database. Which TWO actions should be taken to achieve this resilience? (Choose two.)

Accepted Answer

Configure the Auto Scaling group to launch EC2 instances in at least two Availability Zones.. Option D is correct because an Auto Scaling group configured to span at least two Availability Zones ensures that if one AZ fails, the remaining AZ can continue serving traffic behind the ALB, maintaining compute capacity and application availability. Option E is correct because an RDS for MySQL Multi-AZ deployment maintains a synchronous standby replica in a different AZ and automatically fails over to it if the primary AZ becomes unavailable, providing database resilience. Option A is incorrect because a read replica is asynchronous and is intended for read scaling, not automatic failover for high availability. Option B is incorrect because a Single-AZ RDS database has no standby in another AZ and cannot survive an AZ failure. Option C is incorrect because placing all EC2 instances in one AZ concentrates the workload in a single failure domain, defeating the resilience requirement.

Answer

Configure an RDS read replica in a different Availability Zone.

Answer

Use a Single-AZ RDS for MySQL database to keep costs low.

Answer

Place all EC2 instances in the same Availability Zone to reduce cross-AZ data transfer costs.

Question 10

A company runs a critical application on AWS using Amazon EC2 instances in an Auto Scaling group, an Application Load Balancer (ALB), and an Amazon RDS for PostgreSQL Multi-AZ DB cluster. The application must maintain an RTO of 5 minutes and an RPO of 1 second for database transactions. The current setup meets these requirements, but the DevOps team wants to improve the resilience of the application tier to withstand a regional failure. Which THREE actions should be taken? (Choose three.)

Accepted Answer

Replace the RDS Multi-AZ cluster with Amazon Aurora Global Database to replicate data across regions.. Amazon Aurora Global Database is the correct choice because it provides cross-region replication with a typical RPO of 1 second and RTO of 1 minute, meeting the stated requirements. Unlike standard RDS Multi-AZ, which is limited to a single region, Aurora Global Database replicates data asynchronously across multiple regions with minimal lag, ensuring the database tier can survive a regional failure while maintaining the required RPO of 1 second.

Answer

Use Amazon EFS Replication to replicate application data across regions with a recovery point objective (RPO) of 1 second.

Answer

Extend the existing Auto Scaling group to launch instances in two regions by specifying a second region in the launch template.

Question 11

A company runs a production e-commerce platform on AWS. The architecture includes an Application Load Balancer (ALB) that distributes traffic to a fleet of Amazon EC2 instances running in an Auto Scaling group across three Availability Zones (AZs). The application stores session state in Amazon ElastiCache for Redis (cluster mode disabled) with a single node. The database is an Amazon Aurora MySQL DB cluster with one writer and two reader instances in different AZs. The platform experiences intermittent slowdowns and occasional timeouts during peak traffic hours. The CloudWatch metrics show that the ALB's TargetResponseTime is elevated, and the Redis CPU utilization is consistently above 80% during these periods. The Auto Scaling group is scaling out, but new instances take several minutes to become healthy. The DevOps team has been asked to improve the resilience and performance of the application with minimal changes to the application code. Which solution should the team implement?

Accepted Answer

Migrate ElastiCache for Redis to a cluster mode enabled configuration with multiple shards and enable Multi-AZ with automatic failover. Also, use an ElastiCache replication group with read replicas in different AZs.. The primary bottleneck is the single-node Redis instance (CPU > 80%), which cannot scale horizontally and lacks high availability. Migrating to cluster mode enabled with multiple shards distributes CPU load across shards, while Multi-AZ with automatic failover and read replicas in different AZs provides high availability and read scaling. This directly addresses the elevated ALB TargetResponseTime caused by Redis latency. Note that the application will need to use a Redis Cluster-compatible client; since the stem allows minimal code changes, this solution is still appropriate.

Answer

Replace the ALB with a Network Load Balancer (NLB) to reduce latency, and use an Auto Scaling group with a step scaling policy based on Redis CPU utilization.

Answer

Increase the instance size of the ElastiCache for Redis node and the size of the Aurora writer instance. Also, increase the cooldown period for the Auto Scaling group to allow new instances to warm up.

Answer

Implement Amazon RDS Proxy in front of the Aurora cluster to reduce database connection overhead, and increase the size of the Redis instance to handle more connections.

Question 12

A company runs a critical web application on Amazon EC2 instances behind an Application Load Balancer (ALB) across multiple Availability Zones. The application stores session data in a shared Amazon ElastiCache for Redis cluster. The operations team reports that during a recent AZ failure, users experienced session loss and application errors. Which combination of actions should the company take to improve resilience and maintain session state during an AZ failure? (Choose TWO.)

Accepted Answer

Configure the ALB with cross-zone load balancing enabled and connection draining set to a suitable timeout.. Enabling cross-zone load balancing on the ALB ensures traffic is distributed evenly across all EC2 instances in all AZs, and connection draining with a suitable timeout allows in-flight requests to complete before instances are deregistered, preventing session loss during an AZ failure. Option C is correct because enabling cluster mode for ElastiCache for Redis with replica nodes in different AZs provides automatic sharding and replication, ensuring session data remains available and consistent even if a primary node in one AZ fails. Option E is incorrect because while ElastiCache for Redis supports Multi-AZ with automatic failover, it alone does not guarantee that replica nodes are placed in different Availability Zones for each shard; enabling cluster mode with replicas in different AZs (Option C) provides a more comprehensive solution for maintaining session state during an AZ failure.

Answer

Deploy an Auto Scaling group with a dynamic scaling policy that adds instances in the remaining AZs.

Answer

Configure the application to use a custom DNS name with a low TTL pointing to the ElastiCache cluster endpoint.

Answer

Enable Multi-AZ for the ElastiCache cluster to automatically fail over to a replica in another AZ.

Question 13

A company runs a stateless web application on EC2 instances in an Auto Scaling group across three Availability Zones. The application uses an Application Load Balancer. The operations team needs to ensure that the application remains available if one AZ fails. Which solution is MOST resilient?

Accepted Answer

Configure the Auto Scaling group to launch instances in three Availability Zones with a desired capacity of 3.. Distributing instances across three Availability Zones (AZs) with a desired capacity of 3 ensures that even if one AZ fails, the remaining two AZs still have at least 2 instances running, maintaining service capacity. The Application Load Balancer (ALB) automatically routes traffic away from the failed AZ, and the Auto Scaling group will replace lost instances in the healthy AZs, providing the highest resilience against a single-AZ failure.

Answer

Configure the Auto Scaling group to launch instances in a single Availability Zone with a desired capacity of 6.

Answer

Configure the Auto Scaling group to launch instances in two Availability Zones with a desired capacity of 4.

Answer

Configure the Auto Scaling group to launch instances in two Availability Zones with a desired capacity of 6, all in one AZ.

Question 14

Drag and drop the steps to troubleshoot a failed deployment in AWS CodeDeploy into the correct order.

Accepted Answer

Check CodeDeploy Console → Review Agent Logs → Validate AppSpec File → Verify Instance Configuration → Redeploy. Troubleshooting starts with console, then agent logs, then AppSpec, then instance configuration, then redeploy.

Answer

Review Agent Logs → Check CodeDeploy Console → Validate AppSpec File → Verify Instance Configuration → Redeploy

Answer

Validate AppSpec File → Check CodeDeploy Console → Review Agent Logs → Verify Instance Configuration → Redeploy

Answer

Redeploy → Check CodeDeploy Console → Review Agent Logs → Validate AppSpec File → Verify Instance Configuration

Question 15

Drag and drop the steps to perform a disaster recovery failover from a primary region to a secondary region using AWS Route 53 and RDS.

Accepted Answer

Configure health checks, then lower TTL, then promote RDS, then update DNS, then verify. First configure health checks, then lower TTL, then promote RDS, then update DNS, then verify.

Answer

Lower TTL, then configure health checks, then promote RDS, then update DNS, then verify

Answer

Configure health checks, then promote RDS, then lower TTL, then update DNS, then verify

Answer

Configure health checks, then update DNS, then lower TTL, then promote RDS, then verify