DOP-C02 Resilient Cloud Solutions Practice Test 14 — 15 Questions

Question 1

A company runs a web application on EC2 instances behind an ALB. To improve resilience, they want to automatically replace failed instances and maintain a minimum number of instances. Which AWS service should be used?

Accepted Answer

Amazon EC2 Auto Scaling. Auto Scaling is designed to automatically replace failed instances and maintain a desired capacity, improving resilience.

Answer

AWS CloudFormation

Answer

AWS Elastic Beanstalk

Answer

AWS Systems Manager

Question 2

A company's production database on Amazon RDS Multi-AZ DB instance experienced a failover. The application experienced a brief outage. How can the company reduce the failover time?

Accepted Answer

Use Amazon RDS Proxy. Using RDS Proxy reduces failover time by maintaining connections and routing them to the new primary instance quickly.

Answer

Switch to a Single-AZ deployment

Answer

Increase the DB instance size

Answer

Enable Enhanced Monitoring

Question 3

A company uses AWS Lambda functions to process events from Amazon SQS. The Lambda function sometimes fails due to timeouts. The team wants to preserve the event for reprocessing. How should they configure the integration?

Accepted Answer

Set up a DLQ on the SQS queue that receives the events. By configuring a dead-letter queue (DLQ) on the SQS queue, failed messages are preserved for later reprocessing.

Answer

Use Lambda reserved concurrency

Answer

Enable Lambda function DLQ with SNS topic

Answer

Increase Lambda timeout to maximum

Question 4

A company wants to design a disaster recovery solution for its primary AWS Region. The solution should have a Recovery Point Objective (RPO) of a few seconds and a Recovery Time Objective (RTO) of a few minutes. Which strategy meets these requirements?

Accepted Answer

Multi-Region active-active. A multi-Region active-active setup with synchronous replication provides near-zero RPO and minimal RTO.

Answer

Pilot light

Answer

Backup and restore

Answer

Warm standby

Question 5

An application on EC2 instances in an Auto Scaling group uses an ALB. The ALB health checks are failing for some instances, but the instances are healthy from the OS perspective. What is the most likely cause?

Accepted Answer

The security group for the instances does not allow traffic from the ALB. Misconfigured security group rules can block health check traffic, causing the ALB to mark instances as unhealthy.

Answer

The ALB idle timeout is too low

Answer

The Auto Scaling group cooldown period is too short

Answer

The ALB cross-zone load balancing is disabled

Question 6

A company is building a global application that requires low-latency access to static content across multiple AWS Regions. The content changes infrequently. Which solution is MOST resilient and cost-effective?

Accepted Answer

Use Amazon CloudFront with an S3 bucket as origin. CloudFront with an S3 origin provides global edge caching, low latency, and high resilience at low cost.

Answer

Use Amazon S3 Transfer Acceleration

Answer

Set up a VPN to a single Region

Answer

Deploy EC2 instances in each Region with a global load balancer

Question 7

A company wants to ensure its Amazon RDS DB instance is highly available with automatic failover in case of an AZ failure. Which configuration should they use?

Accepted Answer

Multi-AZ deployment. Multi-AZ deployment provides automatic failover to a standby instance in another AZ.

Answer

Amazon RDS Proxy

Answer

Single-AZ with automated backups

Answer

Read replicas in multiple AZs

Question 8

A company runs a stateful application on EC2 instances. The application stores session data locally. The instances are behind an ALB with sticky sessions enabled. A scaling event terminates an instance, causing loss of session data. How can the company prevent this while maintaining performance?

Accepted Answer

Use Amazon ElastiCache to store session data. Using ElastiCache for session storage externalizes session data, making it resilient to instance termination.

Answer

Use a dedicated EC2 instance for sessions

Answer

Disable sticky sessions

Answer

Increase the sticky session duration

Question 9

A company's application on Amazon ECS experiences intermittent failures when the task attempts to access an S3 bucket. The task role has the correct S3 permissions. What is the most likely cause?

Accepted Answer

The S3 bucket policy explicitly denies access from the task's VPC. If the S3 bucket policy denies access from the task's VPC or source, it can cause intermittent failures.

Answer

The task is using the wrong IAM role

Answer

The S3 bucket is in a different region

Answer

The S3 bucket has public access blocked

Question 10

A company is designing a resilient architecture for a critical application. Which TWO strategies improve resilience?

Accepted Answer

Deploy resources across multiple Availability Zones. Multi-AZ deployments and health checks with auto-remediation improve resilience by handling failures automatically.

Answer

Use a single large instance instead of multiple smaller ones

Answer

Disable automated backups to reduce latency

Answer

Deploy resources in a single Availability Zone

Question 11

A company runs a microservices architecture on Amazon ECS. They want to ensure that if a service fails, it does not cascade to other services. Which TWO design patterns should they implement?

Accepted Answer

Circuit breaker pattern. Circuit breaker prevents cascading failures, and bulkheads isolate failures to specific services.

Answer

Cache-aside pattern

Answer

Saga pattern

Answer

Throttling pattern

Question 12

A company wants to protect its application from DDoS attacks. Which THREE AWS services should they use?

Accepted Answer

AWS WAF. AWS Shield Advanced, WAF, and CloudFront provide layered DDoS protection.

Answer

Amazon Inspector

Answer

Amazon GuardDuty

Question 13

A company is deploying a critical application on Amazon EC2 instances behind an Application Load Balancer (ALB) across multiple Availability Zones. The application must be resilient to the failure of an entire Availability Zone. Which design should the company implement?

Accepted Answer

Launch EC2 instances in at least two Availability Zones and place them behind an Application Load Balancer with cross-zone load balancing enabled.. Option A is correct because deploying EC2 instances across at least two Availability Zones (AZs) behind an Application Load Balancer (ALB) with cross-zone load balancing enabled ensures that if an entire AZ fails, the ALB can route traffic to healthy instances in the remaining AZs. Cross-zone load balancing allows the ALB to distribute incoming requests evenly across all registered instances in all enabled AZs, which improves fault tolerance and resource utilization. This design meets the requirement for resilience to an AZ failure by eliminating a single point of failure at the AZ level.

Answer

Use one EC2 instance in a single Availability Zone behind a Network Load Balancer.

Answer

Launch EC2 instances in one Availability Zone and use an Application Load Balancer to distribute traffic.

Answer

Deploy EC2 instances in two Availability Zones but use a single Application Load Balancer in one AZ.

Question 14

A DevOps team is designing a disaster recovery solution for an Amazon RDS for MySQL database. The primary database is in us-east-1, and the recovery point objective (RPO) is 5 minutes, recovery time objective (RTO) is 1 hour. Which solution meets these requirements?

Accepted Answer

Create a cross-Region read replica in the secondary Region.. A cross-Region read replica in the secondary Region meets the RPO of 5 minutes because replication from the primary RDS instance to the read replica is asynchronous but typically completes within seconds to a few minutes, well under the 5-minute threshold. In a disaster, promoting the read replica to a standalone instance can be done manually or automated, and the RTO of 1 hour is achievable because promotion takes only a few minutes, leaving ample time for DNS and application failover. This solution provides a continuous replication stream without manual intervention, unlike snapshot-based approaches.

Answer

Enable Multi-AZ deployment for high availability.

Answer

Take manual snapshots and copy them to the secondary Region daily.

Answer

Configure automated backups with a retention period of 35 days.

Question 15

A company runs a stateless web application on Amazon ECS with Fargate launch type. The application experiences intermittent traffic spikes. The company wants to ensure that the application can scale automatically and remain resilient to underlying infrastructure failures. Which combination of actions should the DevOps engineer take?

Accepted Answer

Configure an Application Auto Scaling target tracking policy based on memory utilization and enable Amazon ECS service auto-recovery.. Option D is correct because it combines Application Auto Scaling target tracking based on memory utilization, which is a relevant metric for a stateless web application to handle traffic spikes, with Amazon ECS service auto-recovery, which automatically replaces unhealthy tasks to ensure resilience against underlying infrastructure failures. This approach provides both automatic scaling and fault tolerance without manual intervention.

Answer

Configure a scheduled scaling policy for the Amazon ECS service to add tasks during known peak hours.

Answer

Launch tasks in a single Availability Zone and use an Application Auto Scaling target tracking policy based on CPU utilization.

Answer

Configure a step scaling policy for the Amazon ECS service and increase the task memory size.