DOP-C02 Resilient Cloud Solutions Practice Test 6 — 15 Questions

Question 1

A company uses an Application Load Balancer (ALB) to distribute traffic to EC2 instances. The ALB is in us-east-1a and us-east-1b. They want to ensure that if one AZ fails, traffic is routed only to healthy instances in the other AZ. What configuration is necessary?

Accepted Answer

Enable cross-zone load balancing on the ALB. Cross-zone load balancing must be enabled on the ALB so that traffic can be distributed across instances in all AZs. If disabled, each AZ receives traffic only from its own subnet. Option B is wrong because health checks are already required. Option C is wrong because stickiness doesn't affect failover. Option D is wrong because enabling more AZs helps but without cross-zone balancing, traffic may not be evenly distributed.

Answer

Enable sticky sessions (session affinity)

Answer

Configure health checks on the target group

Answer

Add more subnets in additional AZs

Question 2

A company is designing a highly available architecture for a stateless web application using AWS services. Which TWO steps should they take to achieve high availability?

Accepted Answer

Deploy EC2 instances in multiple Availability Zones. Deploying across multiple AZs ensures availability during AZ failure. An ALB distributes traffic and performs health checks. Option C is wrong because M5 instances are not required. Option D is wrong because EBS is not stateless; better to use ephemeral or S3. Option E is wrong because it's an anti-pattern.

Answer

Store session state in an EBS volume attached to each instance

Answer

Use a single NAT instance in a public subnet

Answer

Use only M5 instance types for better performance

Question 3

A company uses DynamoDB global tables for a multi-region application. They notice that write conflicts are occurring. Which TWO strategies can reduce write conflicts?

Accepted Answer

Use conditional writes in the application code. Using conditional writes ensures no overwrites unless condition is met, reducing conflicts. Application-level conflict resolution can handle conflicts when they occur. Option C is wrong because increasing WCU does not reduce conflicts. Option D is wrong because last writer wins is default and may cause data loss. Option E is wrong because reducing read capacity is irrelevant.

Answer

Reduce read capacity units to limit concurrent reads

Answer

Enable DynamoDB Streams with last writer wins

Answer

Increase write capacity units on the table

Question 4

A company is designing a disaster recovery plan for an RDS PostgreSQL database. They have a cross-region read replica. Which THREE steps should they take to ensure a successful failover?

Accepted Answer

Configure applications to use the new database endpoint. Promoting the read replica makes it a standalone master. Updating Route 53 DNS to point to the new master ensures traffic routing. Ensuring applications can connect to the new endpoint is critical. Option D is wrong because automated backups are separate. Option E is wrong because read replica does not have Multi-AZ by default, but can be enabled after promotion.

Answer

Enable automated backups on the replica before promotion

Answer

Enable Multi-AZ on the read replica before promotion

Question 5

A company runs a critical web application on EC2 instances behind an Application Load Balancer (ALB) across multiple Availability Zones. During a recent failure of one AZ, the application experienced downtime because the Auto Scaling group did not launch new instances quickly enough. What should a DevOps engineer do to improve resilience?

Accepted Answer

Configure the Auto Scaling group to span multiple AZs and enable health checks to replace unhealthy instances.. Option D is correct because distributing instances across multiple AZs ensures that failure of one AZ does not affect the entire application, and using a multi-AZ deployment with proper Auto Scaling group configuration is a best practice for high availability. Option A is wrong because increasing instance size does not mitigate AZ failure. Option B is wrong because a single AZ still presents a single point of failure. Option C is wrong because using a larger AMI does not help with resilience.

Answer

Use a larger AMI to reduce boot times.

Answer

Increase the instance size of the EC2 instances to handle more traffic.

Answer

Configure the Auto Scaling group to launch instances in a single AZ with a larger instance count.

Question 6

An application running on Amazon ECS with Fargate experiences intermittent failures. The task definition includes a single container with a health check command. Despite the health check passing, the application occasionally returns HTTP 500 errors. The application logs are sent to CloudWatch Logs. What is the MOST likely root cause?

Accepted Answer

The health check command only checks the process status, not the application's ability to serve requests.. Option C is correct because if the health check does not verify the application's ability to serve requests (e.g., only checking the process), it can report healthy even when the application is failing. Option A is wrong because ECS service auto scaling does not cause intermittent failures. Option B is wrong because a container port mismatch would cause persistent failures. Option D is wrong because missing environment variables would cause consistent failures.

Answer

The application is missing environment variables that are required for certain requests.

Answer

The ECS service is configured with a target tracking scaling policy that reacts too slowly.

Answer

The container port and host port in the task definition do not match the ALB target group port.

Question 7

A company wants to ensure its data in Amazon S3 is protected against accidental deletion. The bucket stores critical documents. Which approach provides the HIGHEST level of resilience?

Accepted Answer

Enable versioning and MFA delete on the bucket.. Option D is correct because enabling versioning and MFA delete provides protection against both accidental overwrites and malicious deletions. Option A is wrong because lifecycle policies do not protect against deletion. Option B is wrong because cross-region replication protects against region failure but not accidental deletion. Option C is wrong because bucket policies only control access, not deletion recovery.

Answer

Apply a bucket policy that denies s3:DeleteObject for all users.

Answer

Enable S3 lifecycle policies to archive objects to Glacier.

Answer

Configure cross-region replication (CRR) to another bucket.

Question 8

A DevOps team uses AWS CodePipeline to deploy a web application. The pipeline has a deploy stage that uses CodeDeploy to deploy to an Auto Scaling group. During deployment, the new instances fail health checks and the deployment rolls back. However, the rollback also fails because the old instances have been terminated. What should the team do to avoid this issue?

Accepted Answer

Use a blue/green deployment strategy in CodeDeploy to keep the old instances running until the new ones pass health checks.. Option B is correct because using a blue/green deployment with CodeDeploy allows the old instances to remain until the new ones are verified healthy. Option A is wrong because increasing the health check grace period does not help if instances are unhealthy. Option C is wrong because manual approval does not prevent the rollback failure. Option D is wrong because creating a new Auto Scaling group does not inherently solve the termination issue.

Answer

Increase the health check grace period in the Auto Scaling group.

Answer

Add a manual approval step before the deploy stage.

Answer

Configure the pipeline to deploy to a new Auto Scaling group each time.

Question 9

A company runs a stateful application on EC2 instances with instance store volumes. The application requires low-latency access to data. The operations team needs to ensure that instance failure does not result in data loss. Which solution is MOST resilient?

Accepted Answer

Replicate data in real time to an EBS volume and take periodic snapshots.. Option D is correct because replicating data to EBS and taking snapshots provides persistent storage and disaster recovery. Option A is wrong because instance store volumes are ephemeral. Option B is wrong because increasing instance size does not prevent data loss. Option C is wrong because an AMI does not capture data from instance store volumes.

Answer

Use instance store volumes with RAID 1 across multiple instances.

Answer

Use larger instance types with more instance store capacity.

Answer

Create an AMI of the instance periodically to capture the data.

Question 10

A company is using Amazon RDS for MySQL with Multi-AZ deployment. During a recent failover, the application experienced a brief downtime because the DNS cache on the application servers still pointed to the old primary. How can a DevOps engineer minimize this downtime?

Accepted Answer

Use an RDS Proxy to manage connections and reduce DNS dependency.. Option C is correct because using an RDS proxy provides a stable endpoint and connection pooling, reducing failover impact. Option A is wrong because increasing TTL increases the caching duration, worsening the issue. Option B is wrong because the CNAME is automatically updated by RDS, but DNS propagation takes time. Option D is wrong because there is no dedicated endpoint for Multi-AZ; the same CNAME is used.

Answer

Configure the application to use the Multi-AZ endpoint instead of the primary endpoint.

Answer

Configure application servers to use a hardcoded IP address instead of the RDS endpoint.

Answer

Increase the TTL on the RDS DNS record.

Question 11

A company uses AWS Lambda to process messages from an Amazon SQS queue. The Lambda function occasionally times out after 15 seconds. To improve resilience, the team wants to ensure messages are not lost and are retried. Which configuration is MOST appropriate?

Accepted Answer

Increase the Lambda timeout to 30 seconds and configure a dead-letter queue (DLQ) for the SQS queue.. Option B is correct because increasing the visibility timeout to allow Lambda to process and leveraging dead-letter queue for failed messages ensures no messages are lost. Option A is wrong because reducing timeout worsens the issue. Option C is wrong because removing the DLQ loses failed messages. Option D is wrong because batching does not help with timeout.

Answer

Reduce the Lambda timeout to 5 seconds to fail fast and retry quickly.

Answer

Set the SQS queue visibility timeout to less than the Lambda timeout.

Answer

Increase the batch size and remove the DLQ to speed up processing.

Question 12

A company runs a containerized application on Amazon EKS. The application uses an ALB Ingress Controller. During a cluster upgrade, the ingress controller stops responding, causing downtime. The team wants to ensure resilience during upgrades. Which approach is BEST?

Accepted Answer

Schedule the ingress controller pod on a dedicated node with a taint that prevents node upgrades.. Option A is correct because running the ingress controller on a node that is not upgraded (e.g., using taints/tolerations) ensures the controller remains available. Option B is wrong because a managed node group does not guarantee availability. Option C is wrong because cluster autoscaler does not protect against upgrade. Option D is wrong because HPA does not help with upgrades.

Answer

Use a horizontal pod autoscaler for the ingress controller.

Answer

Enable cluster autoscaler to add more nodes during the upgrade.

Answer

Use a managed node group with a higher instance count.

Question 13

A company uses Amazon CloudFront to distribute content from an S3 bucket origin. Some users report intermittent access errors. The DevOps team suspects the origin is overwhelmed. What is the MOST effective way to improve resilience?

Accepted Answer

Set up an origin failover with two S3 buckets behind an Application Load Balancer (ALB).. Option D is correct because using an ALB or multiple origins with failover provides redundancy and load distribution. Option A is wrong because increasing cache TTL only reduces origin load but does not address origin failures. Option B is wrong because reducing TTL increases origin load. Option C is wrong because CloudFront does not have an origin health check feature; it uses error rate.

Answer

Reduce the CloudFront cache TTL to serve fresher content.

Answer

Increase the CloudFront cache TTL to reduce requests to the origin.

Answer

Configure CloudFront to perform health checks on the origin.

Question 14

A company is designing a disaster recovery (DR) strategy for a critical application that runs on EC2 instances with an RDS database. The DR site must be in a different AWS Region. The Recovery Point Objective (RPO) is 15 minutes, and Recovery Time Objective (RTO) is 1 hour. Which TWO actions should the company take to meet these objectives? (Choose TWO.)

Accepted Answer

Configure Amazon Route 53 with health checks and failover routing to the DR region.. Options C and D are correct. C: RDS cross-Region read replicas can be promoted to become the primary in the DR region, meeting the RPO with minimal data loss. D: Amazon Route 53 health checks and failover routing can redirect traffic to the DR region within the RTO. A is wrong because AMI copying and instance launch can exceed 1 hour. B is wrong because S3 cross-Region replication does not help with EC2 and RDS. E is wrong because CloudFormation alone does not automatically failover.

Answer

Use AWS Backup to copy EC2 AMIs and RDS snapshots to the DR region every 15 minutes.

Answer

Use AWS CloudFormation to pre-provision resources in the DR region manually.

Answer

Configure S3 cross-Region replication for application data stored in S3.

Question 15

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.)

Accepted Answer

Enable ECS Service Connect for inter-service communication to manage traffic distribution.. Options A, C, and E are correct. A: Auto scaling based on target tracking ensures capacity matches demand. C: ECS service connect provides service discovery and connection resilience. E: Graceful shutdown allows in-flight requests to complete. B is wrong because spot instances are not suitable for latency-sensitive workloads. D is wrong because increasing CPU and memory does not solve latency due to traffic spikes.

Answer

Increase the CPU and memory limits in the task definitions.

Answer

Use EC2 launch type with Spot Instances to reduce cost.