DOP-C02 Resilient Cloud Solutions Practice Test 9 — 15 Questions

Question 1

A company has a microservices architecture running on Amazon ECS with Fargate launch type. Each service is deployed in multiple Availability Zones. The services communicate via REST APIs. Recently, a downstream service experienced a partial outage, causing upstream services to time out and leading to cascading failures. The team wants to improve resilience against such failures. Which combination of actions should the DevOps engineer take? (Choose TWO.)

Accepted Answer

Implement circuit breaker patterns in the service clients.. Option A is correct because implementing circuit breakers (e.g., with AWS App Mesh or client libraries) prevents cascading failures by failing fast when a downstream service is unhealthy. Option D is correct because using an asynchronous messaging pattern (SQS, SNS, EventBridge) decouples services, allowing upstream services to continue processing even if downstream is unavailable. Option B (increasing timeouts) could worsen the situation by holding resources longer. Option C (Auto Scaling) helps with capacity but not with handling unavailability. Option E (removing retries) is too drastic and could cause data loss.

Answer

Increase the HTTP timeout values for all service-to-service calls.

Answer

Remove all retry logic from service calls.

Answer

Configure Auto Scaling for all services based on request count.

Question 2

A company is running a critical application on Amazon RDS for PostgreSQL with Multi-AZ deployment. The application performs frequent writes. During a recent failover test, the team observed that the application experienced a 30-second write outage. To minimize downtime during automatic failovers, which configuration change should the DevOps engineer implement? (Choose TWO.)

Accepted Answer

Configure Amazon RDS Proxy in front of the RDS instance.. Option A is correct because using Amazon RDS Proxy reduces failover time by pooling and reusing connections, so the application can resume quickly after failover. Option D is correct because enabling Multi-AZ with automatic failover is already in place, but ensuring the database connections use the RDS endpoint with a short DNS TTL allows faster reconnection. Option B (increasing DB instance size) does not reduce failover time. Option C (enabling Performance Insights) is for monitoring, not failover. Option E (using synchronous replication) is the default for Multi-AZ and does not reduce failover time.

Answer

Enable Performance Insights to monitor database load.

Answer

Use synchronous replication to the standby instance.

Answer

Increase the DB instance class to a larger size.

Question 3

A DevOps engineer is designing a disaster recovery (DR) strategy for a stateless web application running on EC2 instances with an Application Load Balancer. The application stores data in Amazon S3 and uses a DynamoDB table for session data. The primary region is us-east-1 and the DR region is us-west-2. The RTO is 15 minutes and RPO is 1 minute. Which strategy is most cost-effective and meets the requirements?

Accepted Answer

Use a warm standby with a minimal environment in the DR region, using DynamoDB Global Tables and S3 CRR, with Auto Scaling to scale up on failover.. Option C is correct because the application is stateless and uses S3 and DynamoDB. S3 Cross-Region Replication (CRR) can achieve near-real-time replication (RPO < 1 minute). DynamoDB Global Tables provide multi-region active-active replication with sub-second RPO. A pre-configured standby in the DR region (with scaled-down resources) can be quickly scaled up (within RTO) using Auto Scaling and CloudFormation. Option A (pilot light) is less prepared; Option B (warm standby with full capacity) is more costly; Option D (multi-site active-active) is overkill and costly.

Answer

Use a warm standby strategy with a scaled-down but fully functional environment in the DR region.

Answer

Use a multi-site active-active strategy, running the application in both regions with a Route 53 latency-based routing.

Answer

Use a pilot light strategy with CloudFormation templates to provision resources in the DR region on failure.

Question 4

A company runs a containerized application on Amazon ECS with Fargate. The application uses an Application Load Balancer (ALB) and stores data in Amazon Aurora Serverless v2. The application experiences intermittent timeouts during periods of rapid scaling. The DevOps engineer notices that the Aurora database's ACU utilization spikes to 100% during these events. What should the engineer do to improve resilience? (Choose THREE.)

Accepted Answer

Implement exponential backoff and jitter in application retry logic.. Option A is correct because enabling Aurora Auto Scaling with a higher maximum ACU allows the database to handle bursts. Option B is correct because using RDS Proxy reduces connection overhead and helps manage scaling. Option C is correct because implementing exponential backoff and jitter in application retries prevents thundering herd. Option D (increasing ECS task memory) does not address database bottleneck. Option E (using ElastiCache) could offload reads but not writes; the issue is write-heavy scaling.

Answer

Increase the Fargate task memory and CPU limits.

Answer

Add Amazon ElastiCache in front of the database for caching.

Question 5

A company uses AWS CloudFormation to deploy infrastructure. The DevOps team wants to ensure that if a stack update fails, the stack automatically rolls back to the previous known good state. The team also wants to receive notifications of the rollback. Which combination of steps should the team take? (Choose THREE.)

Accepted Answer

Set the 'Rollback on failure' option to 'Yes' in the CloudFormation stack properties.. Option A is correct because CloudFormation stack updates can be configured with a rollback on failure. Option B is correct because CloudFormation can send events to Amazon SNS, which can then trigger notifications (e.g., email). Option C is correct because enabling termination protection prevents accidental deletion of the stack. Option D (CloudWatch Logs) is for logging, not rollback. Option E (drift detection) is for detecting manual changes, not rollback.

Answer

Create a CloudWatch Logs log group and subscribe to stack events.

Answer

Enable drift detection on the CloudFormation stack.

Question 6

A DevOps engineer is troubleshooting an issue where an EC2 instance behind an ALB target group is marked as unhealthy. The instance i-0abcd1234efgh5678 is serving traffic but the health check is timing out. The security group for the instance allows inbound HTTP from the ALB's security group. What is the most likely cause?

Accepted Answer

The instance's web server is overloaded and not responding within the health check interval.. Option D is correct because the health check is timing out, which suggests the instance is not responding within the timeout period. The instance may be busy or the health check path may be slow. Option A (security group) is already allowed. Option B (subnet) doesn't cause timeout. Option C (health check path) could be a cause if it's incorrect, but timing out indicates the request is reaching the instance but not getting a response in time.

Answer

The instance is in a private subnet with no route to the internet.

Answer

The health check path is misconfigured and returns a 404 status code.

Answer

The security group of the ALB does not allow outbound traffic to the instance.

Question 7

A DevOps engineer created this IAM policy for a CI/CD pipeline role. The pipeline needs to stop and start production EC2 instances and manage Auto Scaling groups. However, the pipeline fails when trying to stop an instance. What is the most likely reason?

Accepted Answer

The instance does not have the tag 'Environment' with value 'production'.. Option B is correct because the ec2:StartInstances and ec2:StopInstances actions are resource-level actions, but the Condition in the first statement requires the resource tag to be 'Environment':'production'. If the instance does not have that tag, the action is denied. The second statement allows Auto Scaling actions without conditions. Option A (ec2:DescribeInstances) is allowed. Option C (Auto Scaling actions) are allowed. Option D (stop operations require stop permission) is not accurate because the permission exists but is conditional.

Answer

The policy does not allow ec2:DescribeInstances for all instances.

Answer

The policy does not allow autoscaling:UpdateAutoScalingGroup for instances.

Answer

The ec2:StopInstances action requires an additional ec2:DescribeInstanceStatus permission.

Question 8

A DevOps engineer is reviewing a CloudFormation template for an S3 bucket that stores application logs. The bucket has versioning enabled and a lifecycle rule to expire noncurrent versions after 30 days. The bucket policy allows public read access to all objects. The company's security policy requires that all S3 buckets block public access. Which change should the engineer make to comply?

Accepted Answer

Remove the bucket policy statement that grants public access.. Option A is correct because the bucket policy currently allows public read access. To block public access, the engineer can either remove the bucket policy statement that grants public access or enable the 'Block all public access' setting on the bucket. Option B (removing the lifecycle rule) is unrelated. Option C (enabling encryption) is a good practice but does not block public access. Option D (changing bucket name) does not affect public access.

Answer

Change the bucket name to include 'private'.

Answer

Enable default encryption on the bucket.

Answer

Remove the lifecycle rule that expires noncurrent versions.

Question 9

A company has a critical application running on Amazon EC2 instances in an Auto Scaling group. The application writes logs to an Amazon EFS file system. The DevOps team needs to ensure that log data is durable and available even if an Availability Zone fails. The EFS file system is currently in one AZ. What should the team do? (Choose TWO.)

Accepted Answer

Enable AWS Backup for the EFS file system with daily backups.. Option A is correct because EFS One Zone is not resilient to AZ failure. The team should recreate the file system as EFS Standard (Regional) which stores data across multiple AZs. Option D is correct because enabling backups (e.g., AWS Backup) provides additional durability and point-in-time recovery. Option B (increasing throughput) does not add durability. Option C (using S3) changes the architecture significantly. Option E (mounting from multiple AZs) is possible with EFS Standard but not with One Zone.

Answer

Increase the EFS throughput mode to Provisioned.

Answer

Copy the log files to Amazon S3 using a cron job.

Answer

Configure the EC2 instances to mount the EFS file system from multiple Availability Zones.

Question 10

A company is migrating a monolithic application to a microservices architecture on Amazon EKS. The application uses a relational database. The team wants to ensure that database connections are managed efficiently and that the database can withstand a sudden spike in connections from multiple microservices. Which solution should the DevOps engineer implement? (Choose THREE.)

Accepted Answer

Deploy Amazon RDS Proxy in front of the database.. Option A is correct because RDS Proxy pools and shares database connections, reducing the number of connections to the database. Option D is correct because configuring the database with appropriate max_connections and using Auto Scaling (e.g., Aurora Auto Scaling) helps handle spikes. Option E is correct because using a connection pool sidecar (e.g., PgBouncer) in the EKS pods adds connection pooling at the application level. Option B (direct connections) would increase load. Option C (ElastiCache) is for caching, not connection management.

Answer

Use direct database connections from each microservice pod.

Answer

Use Amazon ElastiCache for Redis to cache database query results.

Question 11

A company runs a serverless application using AWS Lambda functions behind an Amazon API Gateway. The application processes user uploads stored in an S3 bucket. The Lambda function writes results to a DynamoDB table. Recently, the function started timing out when processing large files. What should the DevOps engineer do to improve resilience for large file processing?

Accepted Answer

Use S3 event notifications to trigger an AWS Step Functions workflow that processes the file asynchronously.. Option B is correct because Lambda has a maximum execution timeout of 15 minutes. For large files, using S3 event notifications to trigger an asynchronous step function or using S3 batch operations is more resilient. Option A (increasing timeout) might not be enough if the file is very large. Option C (ElastiCache) is not relevant. Option D (increasing memory) might help but still has timeout limits.

Answer

Increase the Lambda function memory to improve CPU performance.

Answer

Increase the Lambda function timeout to the maximum 15 minutes.

Answer

Add Amazon ElastiCache to cache processed results and reduce Lambda execution time.

Question 12

A company runs a web application on EC2 instances in an Auto Scaling group across three Availability Zones. The application uses an Application Load Balancer (ALB) and stores session data in an ElastiCache for Redis cluster with cluster mode enabled. During a recent deployment, a new version of the application caused a memory leak in the Redis cluster, leading to out-of-memory errors and evictions. The DevOps team wants to prevent future deployments from affecting the Redis cluster's health. What should the team do? (Choose TWO.)

Accepted Answer

Implement a blue/green deployment strategy using a separate Redis cluster for the new version.. Option A is correct because using a blue/green deployment with a separate Redis cluster for the new version isolates the risk. Option E is correct because enabling CloudWatch alarms on Redis memory usage and evictions can trigger automatic rollback or alerting. Option B (increasing instance size) treats the symptom, not the cause. Option C (snapshot before deployment) is good for backup but doesn't prevent impact. Option D (cluster mode disabled) reduces scalability.

Answer

Increase the ElastiCache node type to a larger instance size.

Answer

Disable cluster mode on the Redis cluster to reduce overhead.

Answer

Take a manual snapshot of the Redis cluster before each deployment.

Question 13

A company runs a critical application on Amazon RDS for MySQL with Multi-AZ deployment. The database is 2 TB in size. The DevOps team needs to perform a major version upgrade (e.g., MySQL 5.7 to 8.0) with minimal downtime. The RTO is 5 minutes and RPO is 1 minute. Which approach should the team take?

Accepted Answer

Create a read replica of the database in the same region, upgrade the replica to the new version, and then promote it to primary.. Option B is correct because creating a read replica, upgrading it, and then promoting it to primary with minimal downtime (cutover) achieves very low downtime. The replica syncs continuously, so RPO is near zero. Option A (in-place upgrade) causes downtime. Option C (DMS) is for migration, not upgrade, and may have longer downtime. Option D (snapshot restore) has significant downtime.

Answer

Take a snapshot of the database, restore it as a new instance, upgrade the restored instance, and redirect traffic.

Answer

Perform an in-place major version upgrade directly on the primary instance.

Answer

Use AWS Database Migration Service (DMS) to migrate data to a new database instance with the upgraded version.

Question 14

Your company runs a multi-tier web application on AWS. The web tier consists of EC2 instances behind an Application Load Balancer (ALB) in an Auto Scaling group across three Availability Zones. The application tier runs on a separate Auto Scaling group of EC2 instances that process requests from the web tier. The database tier uses an Amazon RDS for PostgreSQL Multi-AZ deployment. All application servers write logs to Amazon CloudWatch Logs. Recently, the operations team reported that during peak hours, the web tier experiences intermittent 503 errors. The ALB access logs show that the errors occur when the target group's healthy host count drops to zero momentarily. The Auto Scaling group's minimum and desired capacity is 6, with a maximum of 12. The scaling policy is based on average CPU utilization, with a target of 60%. The health check grace period is 300 seconds. The application health check endpoint returns a 200 status when healthy. The DevOps engineer suspects that the scaling policy is too slow to react to traffic spikes. The engineer wants to implement a more proactive scaling approach. Which solution should the engineer implement?

Accepted Answer

Implement a predictive scaling policy combined with dynamic scaling to proactively adjust capacity based on forecasted traffic.. Option D is correct because using a predictive scaling policy combined with dynamic scaling provides a proactive approach that anticipates traffic patterns and adjusts capacity in advance. Option A (increasing health check grace period) does not help with scaling speed. Option B (step scaling with a lower cooldown) is reactive and may still cause dips. Option C (scheduled scaling) works only if traffic patterns are predictable and doesn't handle spikes well.

Answer

Implement a scheduled scaling policy that increases capacity 30 minutes before the expected peak.

Answer

Increase the health check grace period to 600 seconds to give new instances more time to become healthy.

Answer

Switch to a step scaling policy with a lower cooldown period and a greater scaling adjustment.

Question 15

A financial services company runs a critical application on Amazon ECS with Fargate launch type. The application consists of three microservices: Service A (frontend), Service B (processing), and Service C (database access). Services communicate via REST APIs. The application stores data in Amazon Aurora PostgreSQL Serverless v2. The company has a disaster recovery (DR) requirement: RTO of 30 minutes and RPO of 15 minutes. The primary region is us-east-1 and the DR region is us-west-2. The DevOps team has configured cross-region replication for the Aurora database using an Aurora Global Database. The ECS services are deployed with a service-linked role for Fargate. The team wants to automate the failover process to meet the RTO. Which solution should the team implement?

Accepted Answer

Use AWS CloudFormation StackSets to deploy the ECS services and supporting resources in the DR region. Configure an Aurora Global Database for cross-region replication. Use Amazon Route 53 with health checks and failover routing to automatically redirect traffic to the DR region when the primary region health check fails.. Option A is correct because using CloudFormation StackSets to deploy the infrastructure in both regions and using Route 53 with health checks and failover routing allows automated failover with DNS propagation. The Aurora Global Database provides managed replication. Option B (snapshot restore) is too slow. Option C (manual runbooks) won't meet RTO. Option D (ECS Service Auto Scaling across regions) is not directly possible with Fargate cross-region.

Answer

Take daily snapshots of the Aurora database and copy them to the DR region. In the event of a disaster, restore the snapshot and use AWS CloudFormation to launch the ECS services.

Answer

Use AWS Backup to schedule cross-region backups of the Aurora database every 15 minutes. In the event of a disaster, restore the latest backup and use Elastic Beanstalk to deploy the application in the DR region.

Answer

Configure AWS Global Accelerator with an endpoint group in each region. Use AWS Lambda to periodically check the health of the primary region and update the DNS records manually to point to the DR region.