DOP-C02 Resilient Cloud Solutions Practice Test 5 — 15 Questions

Question 1

A company runs a web application on EC2 instances behind an Application Load Balancer. The application uses an Aurora MySQL database. Recently, the database experienced a failover, and the application started throwing connection errors. The DevOps engineer needs to make the application resilient to database failovers with minimal code changes. What should they do?

Accepted Answer

Configure the application to use the Aurora cluster endpoint for database connections. Using the Aurora cluster endpoint with a read-write endpoint that automatically points to the new writer after a failover ensures the application reconnects without code changes. Option A is wrong because the reader endpoint is for read-only. Option C is wrong because a read replica does not automatically failover. Option D is wrong because RDS proxy does not change the endpoint behavior.

Answer

Configure the application to use the Aurora reader endpoint for all queries

Answer

Create a cross-Region read replica and configure the application to retry on failure

Answer

Use Amazon RDS Proxy with IAM authentication to handle connection pooling

Question 2

A company wants to design a highly available and fault-tolerant architecture for a stateless web application on AWS. Which TWO actions should they take? (Choose two.)

Accepted Answer

Launch EC2 instances in at least two Availability Zones. Deploying EC2 instances in multiple Availability Zones and using an Auto Scaling group ensures fault tolerance and high availability. Option B is wrong because a single instance in one AZ is not fault-tolerant. Option D is wrong because Multi-AZ is for RDS, not for web application instances. Option E is wrong because a single ALB is sufficient; multiple ALBs are not needed.

Answer

Use a single large EC2 instance to simplify management

Answer

Deploy multiple Application Load Balancers in each AZ

Answer

Use an RDS Multi-AZ deployment for the web server fleet

Question 3

A company runs a microservices application on Amazon ECS with Fargate. The services need to be resilient to AZ failures. Which TWO actions should the company take? (Choose two.)

Accepted Answer

Configure the ECS service to spread tasks across multiple Availability Zones. Spreading tasks across multiple AZs and using service auto scaling ensure resilience. Option A is wrong because a single AZ is not resilient. Option C is wrong because Fargate tasks are not attached to EC2 instances. Option E is wrong because a standalone ALB in one AZ is a single point of failure.

Answer

Use a Network Load Balancer in each AZ for the service

Answer

Use a placement group to ensure tasks are launched on the same underlying hardware

Answer

Place all tasks in a single Availability Zone to minimize cross-AZ latency

Question 4

A company is designing a disaster recovery plan for a critical application with an RPO of 15 minutes and RTO of 1 hour. The application runs on EC2 instances with an RDS MySQL database. The primary Region is us-east-1. Which THREE actions should they take to meet the RPO and RTO? (Choose three.)

Accepted Answer

Schedule automated AMI backups of EC2 instances every 15 minutes. Option A is correct because automated AMI backups of EC2 instances every 15 minutes align with the 15-minute RPO by capturing incremental snapshots of the instance volumes. These AMIs can be used to launch replacement EC2 instances in the secondary Region within the 1-hour RTO, provided the infrastructure is pre-staged. The frequency of 15 minutes ensures that data loss is limited to at most 15 minutes of changes.

Answer

Launch EC2 instances in a single Availability Zone in the secondary Region to reduce costs

Answer

Use AWS CloudFormation StackSets to deploy identical infrastructure in the secondary Region

Question 5

An IAM policy is attached to an S3 bucket to allow access from a specific VPC CIDR range. However, users from the VPC are receiving 'Access Denied' errors when trying to access objects in the bucket. What is the MOST likely reason?

Accepted Answer

The condition key 'aws:SourceIp' evaluates the public IP address, but the VPC uses private IP addresses. The condition uses 'aws:SourceIp' which checks the public IP of the request, not the private IP. Since the VPC uses private IPs, the condition fails. Option B is wrong because the policy does not specify sourceVpce. Option C is wrong because the policy does not enforce HTTPS. Option D is wrong because the IAM role does not affect the source IP check.

Answer

The users are assuming an IAM role that does not have permission to access S3

Answer

The policy should use 'aws:sourceVpce' instead of 'aws:SourceIp' to restrict access to a VPC endpoint

Answer

The bucket policy requires HTTPS and the requests are using HTTP

Question 6

A DevOps engineer runs the above command and sees that one target is unhealthy with a 503 error. The application is a web server running on port 80. The health check is configured to hit the root path '/'. Which action should the engineer take to resolve the issue?

Accepted Answer

Verify that the application on the unhealthy instance is configured to respond to '/' with a 200 status code. A 503 error indicates the web server is running but cannot handle the request, likely because the application is not responding correctly to the health check path. Option A is wrong because a 503 means the server is reachable. Option C is wrong because the health check is already on port 80. Option D is wrong because a 503 is not a connection timeout.

Answer

Change the health check port to 443 and use HTTPS

Answer

Increase the health check interval and timeout settings

Answer

Check the security group rules for the target group to ensure port 80 is open

Question 7

A company deploys the above CloudFormation stack. They want to enforce HTTPS for all requests to the S3 bucket. After deployment, users are still able to make HTTP requests. What is the problem?

Accepted Answer

The Deny statement's Resource specifies only the objects, not the bucket itself. The Deny policy only applies to objects in the bucket (Resource: arn:aws:s3:::bucket/*), but not to the bucket itself. Actions like listing objects (s3:ListBucket) are denied only if the resource is the bucket itself. Option A is wrong because the bucket is versioned, but that doesn't affect encryption. Option B is wrong because the Condition is correct. Option D is wrong because the policy uses Deny, which overrides Allow.

Answer

The condition key 'aws:SecureTransport' is misspelled; it should be 'aws:SecureTransport' with a capital 'T'

Answer

The bucket is not versioned, so the policy does not apply to object versions

Answer

The policy uses Deny, but an Allow policy from another statement overrides it

Question 8

A company runs a critical web application on EC2 instances behind an Application Load Balancer. To improve resilience, they want to automatically replace failed instances. Which AWS service should they use?

Accepted Answer

Auto Scaling group with health checks. Auto Scaling automatically replaces unhealthy instances. ELB health checks integration triggers replacement. Option A is wrong because EC2 Instance Recovery only recovers on the same host. Option C is wrong because CloudFormation doesn't auto-replace. Option D is wrong because Systems Manager doesn't replace instances.

Answer

EC2 Instance Recovery

Answer

AWS Systems Manager Automation

Answer

CloudFormation Stack update

Question 9

A company is designing a multi-region active-active architecture for a stateless web application using Route 53 latency-based routing. The application uses an RDS MySQL database. What should be done to ensure database resilience across regions?

Accepted Answer

Create cross-region read replicas and promote to master during failover. Cross-region read replicas can be promoted to master in disaster. Option A is wrong because Aurora Global Database is better but not listed as an option; but read replica promotion is supported. Option B is wrong because Multi-AZ is single-region. Option C is wrong because RDS doesn't support synchronous cross-region replication. Option D is wrong because snapshot restore is manual and slow.

Answer

Configure automated snapshots and copy them to the secondary region

Answer

Use RDS Cross-Region Synchronous Replication

Answer

Enable Multi-AZ deployment in each region

Question 10

A DevOps engineer needs to ensure that an application running on EC2 can automatically recover from an underlying hardware failure without manual intervention. Which AWS feature should be enabled?

Accepted Answer

Configure EC2 Auto Recovery with a CloudWatch alarm. EC2 Auto Recovery automatically recovers an instance if it becomes impaired due to underlying hardware failure. Option B is wrong because termination protection prevents accidental deletion, not recovery. Option C is wrong because detailed monitoring is for CloudWatch. Option D is wrong because placement groups affect performance, not recovery.

Answer

Enable termination protection

Answer

Configure an Auto Scaling group with a minimum size of 1

Answer

Enable CloudWatch detailed monitoring

Question 11

A company is deploying a critical microservice on Amazon ECS with Fargate. They need to ensure that the service can tolerate an Availability Zone failure. What is the BEST approach?

Accepted Answer

Define the service to spread tasks across multiple Availability Zones. Spreading tasks across multiple AZs ensures that if one AZ fails, tasks in other AZs continue. Option A is wrong because Fargate doesn't support instance diversity. Option C is wrong because service auto scaling adds tasks but not across AZs. Option D is wrong because cluster placement constraints are not used with Fargate.

Answer

Use a cluster placement constraint to spread tasks across instances

Answer

Use EC2 launch type and spread tasks across instance types

Answer

Configure service auto scaling to add tasks when CPU is high

Question 12

A company runs an application on EC2 with a shared Elastic IP. The instance fails and an engineer manually attaches the Elastic IP to a standby instance. To automate this failover, which service should be used?

Accepted Answer

CloudWatch Events with a Lambda target. AWS Route 53 health checks can trigger a Lambda function to reassociate the Elastic IP. Option A is wrong because it's a manual feature. Option B is wrong because CloudWatch cannot directly reassociate EIP. Option D is wrong because ASG does not manage Elastic IPs.

Answer

Use an Auto Scaling group with a lifecycle hook

Answer

AWS Elastic Beanstalk

Answer

Configure a second Elastic IP

Question 13

A company wants to protect its S3 bucket data from accidental deletion or overwrite. Which feature should be enabled?

Accepted Answer

Enable S3 Versioning. S3 Versioning keeps all versions, allowing recovery from deletes and overwrites. Option B is wrong because MFA Delete is an additional protection but not the primary. Option C is wrong because bucket policies control access. Option D is wrong because replication is for cross-region copies.

Answer

Enable cross-region replication

Answer

Apply a bucket policy that denies DeleteObject

Answer

Enable MFA Delete

Question 14

A company has a multi-region application with an RDS for MySQL database in us-east-1. They want to minimize downtime if the primary region fails. They set up a cross-region read replica in us-west-2. What additional step is needed for automated failover?

Accepted Answer

Use a custom automation to monitor the primary and promote the replica. Read replicas can be promoted to master, but automated failover requires additional scripting or services. Option A is wrong because RDS does not support cross-region Multi-AZ. Option B is wrong because a single read replica cannot be promoted automatically without custom automation. Option C is wrong because read replicas can be promoted. Option D is correct: you need to implement custom monitoring to promote the replica.

Answer

Create a second read replica in the secondary region

Answer

Configure automatic backup retention on the replica

Answer

Enable Multi-AZ on the read replica

Question 15

A company is designing a disaster recovery strategy for a critical application. They need a Recovery Time Objective (RTO) of 15 minutes and a Recovery Point Objective (RPO) of 1 minute. Which AWS database service configuration meets these requirements?

Accepted Answer

Aurora Global Database. Aurora Global Database provides cross-region replication with sub-second RPO and failover in minutes. Option A is wrong because RDS Multi-AZ is single-region. Option B is wrong because DynamoDB global tables have sub-second RPO but may not meet RTO. Option D is wrong because read replicas have higher RPO.

Answer

RDS MySQL with Multi-AZ and cross-region read replica

Answer

DynamoDB global tables

Answer

RDS PostgreSQL with cross-region read replica