DOP-C02 Resilient Cloud Solutions Practice Test 10 — 15 Questions

Question 1

A startup runs a stateless web application on AWS Elastic Beanstalk with a single environment. The application uses an Amazon RDS for MySQL database instance. The startup is preparing for a marketing campaign that is expected to increase traffic by 10x. The CTO is concerned about the application's ability to handle the load and wants to ensure high availability and resilience. The current architecture has a single RDS instance (db.t3.medium) and a single Elastic Beanstalk environment with one EC2 instance (t3.medium). The startup has a limited budget but wants to improve resilience without over-provisioning. Which combination of actions should the DevOps engineer recommend? (Choose THREE.)

Accepted Answer

Switch the Elastic Beanstalk environment to a load-balanced, auto-scaled environment with a minimum of 2 instances across 2 Availability Zones.. Option A is correct because Elastic Beanstalk can be configured for load-balanced, auto-scaled environments. Option B is correct because Multi-AZ RDS provides high availability for the database. Option C is correct because RDS Proxy helps manage connections efficiently during traffic spikes. Option D (dedicated instances) is costly and not necessary. Option E (ElastiCache) is additional cost; focus on core resilience first.

Answer

Add an Amazon ElastiCache cluster to cache frequent database queries.

Answer

Use dedicated instances for the EC2 instances to ensure consistent performance.

Question 2

A company runs a critical application on AWS Lambda functions that process real-time streaming data from Amazon Kinesis Data Streams. Each Lambda function processes a batch of records and writes results to an Amazon DynamoDB table. The application is sensitive to data loss and requires exactly-once processing semantics. Recently, the operations team observed that the Lambda function is failing intermittently with 'ProvisionedThroughputExceededException' errors from DynamoDB. The Lambda function's batch size is 100, and the function is configured with a reserved concurrency of 500. The DynamoDB table has 100 read capacity units (RCUs) and 100 write capacity units (WCUs) with auto scaling enabled up to 1000 WCUs. The function's execution role has the necessary DynamoDB permissions. The Kinesis stream has 10 shards. The DevOps engineer needs to resolve the throttling errors without losing data. Which combination of actions should the engineer take? (Choose THREE.)

Accepted Answer

Set the Lambda function's batch size to a lower value (e.g., 10) and enable parallelization factor per shard.. Option A is correct because Kinesis supports retries and can reprocess records after failures, ensuring no data loss. Option B is correct because mapping iterator age and using a lower batch size reduces the number of concurrent writes. Option E is correct because enabling DynamoDB auto scaling with a higher maximum WCU ensures the table can handle bursts. Option C (increasing RCU) is not needed for writes. Option D (increasing Lambda concurrency) may increase throttle.

Answer

Increase the DynamoDB table's read capacity units to 1000.

Answer

Increase the Lambda function's reserved concurrency to 1000.

Question 3

A company runs a containerized application on Amazon EKS. The application uses an Application Load Balancer (ALB) as the ingress controller. The DevOps team wants to ensure that the application can automatically recover from node failures. The cluster consists of managed node groups across three Availability Zones. The team noticed that when a node fails, the pods on that node are not rescheduled for several minutes. The team wants to reduce the time to reschedule pods. Which configuration change should the team make?

Accepted Answer

Configure the kubelet on the nodes to have a lower node-monitor-grace-period and pod-eviction-timeout.. Option B is correct because configuring the kubelet with a lower node-monitor-grace-period (e.g., 40 seconds) and pod-eviction-timeout reduces the time before the node is considered unhealthy and pods are evicted. Option A (increasing pod disruption budgets) would delay rescheduling. Option C (node auto-repair) is a managed feature but doesn't directly reduce pod rescheduling time. Option D (cluster autoscaler) adds nodes but does not reduce rescheduling time for existing pods.

Answer

Increase the pod disruption budget for the application deployments.

Answer

Enable the AWS node auto-repair feature on the managed node group.

Answer

Enable cluster autoscaler to add new nodes quickly.

Question 4

A company is deploying a critical web application on AWS and needs to ensure high availability and disaster recovery across multiple AWS Regions. The application uses an Application Load Balancer (ALB) in the primary Region and an Amazon RDS Multi-AZ DB instance. Which TWO actions should the company take to meet these requirements? (Choose two.)

Accepted Answer

Use AWS Global Accelerator with endpoint groups in multiple Regions.. Option B is correct because AWS Global Accelerator provides static IP addresses and routes traffic to the optimal endpoint across regions, supporting active-passive failover. Option E is correct because Route 53 health checks can monitor the primary ALB and automatically failover to a secondary ALB in another region. Option A is wrong because RDS Multi-AZ only provides high availability within a single region, not cross-region disaster recovery. Option C is wrong because Auto Scaling groups are for scaling within a region, not cross-region failover. Option D is wrong because CloudFront is a CDN, not designed for regional failover routing.

Answer

Configure an Amazon RDS Multi-AZ deployment in a secondary Region.

Answer

Set up Amazon CloudFront with multiple origins pointing to each Region's ALB.

Answer

Create an Auto Scaling group in the secondary Region that automatically scales up when the primary fails.

Question 5

A company runs a stateful web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application stores session data in local instance memory. To improve resiliency, the company wants to make the application stateless and distribute the load across multiple Availability Zones. Which THREE actions should the company take? (Choose three.)

Accepted Answer

Configure the ALB to distribute traffic across EC2 instances in multiple Availability Zones.. Option A is correct because ElastiCache provides a centralized, highly available session store. Option B is correct because using an ALB with multiple AZs distributes traffic and provides high availability. Option D is correct because DynamoDB is a fully managed, durable session store. Option C is wrong because sticky sessions (session affinity) are used to route requests to the same instance, which is not ideal for stateless architecture. Option E is wrong because an NLB operates at layer 4 and does not support path-based routing or session management for HTTP applications as effectively as an ALB.

Answer

Enable sticky sessions (session affinity) on the ALB.

Answer

Replace the ALB with a Network Load Balancer (NLB) to improve performance.

Question 6

A company runs a production application on Amazon ECS with Fargate, fronted by an Application Load Balancer (ALB). The application experiences periodic latency spikes and occasional 502 errors. The ECS service is configured with a desired count of 2 tasks, and the ALB health check is set to /health with a 30-second interval and 2 consecutive failures threshold. The team uses CloudWatch Container Insights and has noticed that CPU and memory utilization of tasks remain below 50%. However, the ALB TargetGroup's HealthyHostCount metric occasionally drops to 0 for a few minutes before recovering. The deployment strategy is rolling update with a minimum healthy percent of 50% and maximum percent of 200%. The team recently updated the task definition to increase memory and CPU, but the issue persists. What is the MOST likely cause of the problem?

Accepted Answer

The ALB health check is too aggressive, causing tasks to be marked unhealthy during brief initialization or deployment.. Option B is correct because the health check interval (30 seconds) and failure threshold (2) mean it takes up to 60 seconds to mark a task unhealthy. During deployments, the rolling update may temporarily have only 1 healthy task (minimum 50% of 2 = 1), and if that task becomes unhealthy, HealthyHostCount drops to 0. Option A is wrong because CPU and memory are below 50%, so resource limits are not the issue. Option C is wrong because a target group with 2 tasks and 2 AZs is fine; the problem is not AZ-specific. Option D is wrong because ECS service-linked role does not affect health checks.

Answer

The ECS service role lacks permissions to register targets with the ALB.

Answer

The ALB target group is configured with only one Availability Zone, causing loss of all targets when that AZ fails.

Answer

The task's CPU or memory limits are set too low, causing the container to be throttled.

Question 7

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

Accepted Answer

Auto Scaling group with ELB health checks. Auto Scaling groups with health checks automatically replace unhealthy instances. Option A is wrong because ELB health checks only mark instances unhealthy; replacement requires Auto Scaling. Option C is wrong because CloudWatch alarms trigger actions but not instance replacement. Option D is wrong because Lambda can invoke API calls but is not the native mechanism.

Answer

CloudWatch alarm that terminates the instance

Answer

AWS Lambda function that checks health and launches new instances

Answer

Elastic Load Balancer health checks

Question 8

A company uses Amazon RDS Multi-AZ for disaster recovery. The primary DB instance in us-east-1a fails. What happens next?

Accepted Answer

The standby DB instance in us-east-1b is promoted automatically and the CNAME record is updated. RDS Multi-AZ automatically fails over to the standby in a different Availability Zone within minutes. Option A is wrong because no manual intervention is needed. Option B is wrong because the CNAME automatically updates. Option D is wrong because Multi-AZ provides automatic failover.

Answer

The administrator must manually promote the standby instance

Answer

The primary instance is automatically rebuilt in the same AZ

Answer

A read replica in us-east-1b is automatically promoted to primary

Question 9

A company has a stateless web application on EC2 instances behind an ALB. They want to ensure that if an entire Availability Zone fails, the application remains available with minimal impact. Which architecture best meets this requirement?

Accepted Answer

Deploy the application in two AZs with an Auto Scaling group and an ALB that is enabled for multiple AZs. Using Auto Scaling with multiple AZs and a multi-AZ ALB ensures that if one AZ fails, the ALB routes traffic to healthy instances in other AZs. Option A is wrong because a single AZ is a single point of failure. Option B is wrong because ALB does not automatically shift traffic to another region without Route53. Option D is wrong because spreading instances across AZs but using a single-AZ ALB still risks ALB failure.

Answer

Use a global secondary index in DynamoDB to replicate data across regions

Answer

Deploy EC2 instances in two AZs but use a single-AZ ALB

Answer

Deploy the application in a single AZ with an Auto Scaling group that launches instances in the same AZ

Question 10

A company runs a stateful application on EC2 instances. They want to distribute traffic evenly and maintain session stickiness. Which AWS service should they use?

Accepted Answer

Application Load Balancer with sticky sessions. An Application Load Balancer with sticky sessions (session affinity) ensures that a client's requests are sent to the same target. Option A is wrong because Network Load Balancer does not natively support sticky sessions based on application cookies. Option C is wrong because Route53 weighted routing does not handle session stickiness. Option D is wrong because CloudFront can forward cookies but is not primarily for load balancing.

Answer

Network Load Balancer

Answer

Amazon Route 53 weighted routing policy

Answer

Amazon CloudFront with origin failover

Question 11

A company uses AWS CodeDeploy to deploy a new version of an application to EC2 instances. They want to minimize downtime and roll back quickly if the deployment fails. Which deployment type should they use?

Accepted Answer

Blue/green deployment. Blue/green deployment creates a new environment (green) and shifts traffic after testing, allowing instant rollback by switching back to the original (blue). Option A is wrong because in-place updates cause downtime during the deployment. Option C is wrong because canary is a subset of blue/green but not the full strategy. Option D is wrong because linear is a traffic shifting pattern.

Answer

Canary deployment

Answer

Linear deployment

Answer

In-place deployment

Question 12

A company runs a critical microservices architecture on Amazon ECS with Fargate. They want to ensure that if a task fails, it is automatically restarted, and the service remains available across multiple Availability Zones. How should they configure the ECS service?

Accepted Answer

Define an ECS service with a task definition, set desired count across multiple Availability Zones, and use Service Auto Scaling. Setting the number of tasks across multiple AZs and enabling Service Auto Scaling with task-level restart ensures resilience. The ECS service scheduler automatically restarts failed tasks. Option A is wrong because a single-AZ deployment is a single point of failure. Option B is wrong because placing all tasks in one AZ does not provide AZ resilience. Option D is wrong because a standalone task does not have automatic restart.

Answer

Place all tasks in the same Availability Zone to reduce latency

Answer

Run a standalone Fargate task and use a CloudWatch alarm to restart it

Answer

Use an EC2 launch type with a single instance to reduce complexity

Question 13

A company runs a global web application on EC2 instances behind an ALB in us-east-1. They want to improve resilience by routing users to the nearest healthy region. Which service should they use?

Accepted Answer

Amazon Route 53 latency-based routing with health checks. Amazon Route 53 with latency-based routing and health checks routes users to the region with the lowest latency and only to healthy endpoints. Option A is wrong because CloudFront with multi-region origins requires additional configuration. Option B is wrong because Global Accelerator improves performance but not primarily for routing to nearest region. Option D is wrong because ALB is regional, not global.

Answer

AWS Global Accelerator

Answer

Application Load Balancer cross-zone load balancing

Answer

Amazon CloudFront with multiple origins

Question 14

A company uses Amazon DynamoDB with global tables for a multi-region active-active application. They notice that occasionally, concurrent updates to the same item in different regions cause data inconsistency. How can they resolve this?

Accepted Answer

Use conditional writes and design the application to handle conflicts. Option C is correct because DynamoDB global tables use an eventually consistent model for multi-region replication, meaning concurrent updates to the same item in different regions can lead to conflicts. Conditional writes allow the application to enforce a last-writer-wins (LWW) strategy or custom conflict resolution logic, ensuring data consistency by only applying updates that meet specified conditions (e.g., a version number or timestamp check). This approach aligns with the recommended practice for handling concurrent writes in an active-active global table setup.

Answer

Disable global tables and use a single region

Answer

Use DynamoDB read replicas instead of global tables

Answer

Use DynamoDB Accelerator (DAX) to cache writes

Question 15

A company experiences intermittent high latency for a web application running on EC2 behind an ALB. They want to monitor and automatically replace instances that have high CPU. Which solution meets this requirement?

Accepted Answer

Create a CloudWatch alarm on CPU utilization that triggers an Auto Scaling policy to replace the instance. Option A is correct because you can configure a CloudWatch alarm on the EC2 instance's CPU utilization metric, and then use that alarm to trigger an Auto Scaling lifecycle hook or a scaling policy that terminates the unhealthy instance and launches a replacement. This directly ties performance monitoring to automated instance replacement, meeting the requirement to replace instances with high CPU.

Answer

Use Auto Scaling scheduled scaling actions to replace instances at peak times

Answer

Use AWS Lambda to periodically check CPU and terminate high-CPU instances

Answer

Configure the ALB health check to mark instances unhealthy when CPU is high