DOP-C02 Practice Exam 55 — 20 Questions

Question 1

A company is designing a resilient architecture for a web application using AWS Global Accelerator and two Application Load Balancers in different AWS Regions. The application is stateless and uses a global DynamoDB table for data. What is the primary benefit of using Global Accelerator in this architecture?

Accepted Answer

It provides static IP addresses and automatically routes traffic to the closest healthy ALB, improving availability and performance.. Option B is correct because Global Accelerator provides static IP addresses and directs traffic to the nearest healthy endpoint, improving resilience and performance. Option A is wrong because Global Accelerator does not cache content. Option C is wrong because DNS routing is not the primary benefit; Global Accelerator uses anycast. Option D is wrong because Global Accelerator does not replace ALB; it works with ALBs.

Answer

It replaces the need for an Application Load Balancer.

Answer

It provides DNS-based failover between Regions.

Answer

It caches static content at AWS edge locations.

Question 2

An e-commerce platform uses Amazon DynamoDB as its primary database. The platform experiences occasional read throttling during flash sales. The operations team needs to ensure that read traffic is handled without errors, while keeping costs low. What should a DevOps engineer recommend?

Accepted Answer

Enable DynamoDB Accelerator (DAX) to cache frequently read data.. Option A is correct because DynamoDB Accelerator (DAX) provides an in-memory cache that reduces read load on the database, improving performance and reducing throttling. Option B is wrong because increasing read capacity units increases cost without optimization. Option C is wrong because DynamoDB Streams is for change data capture, not caching. Option D is wrong because Global Tables is for multi-region replication, not read scaling.

Answer

Increase the read capacity units for the table during flash sale events.

Answer

Use DynamoDB Streams to replicate reads to a separate table.

Answer

Implement Global Tables to distribute read traffic across multiple regions.

Question 3

Which TWO strategies can be used to improve the resilience of an application running on Amazon ECS with Fargate? (Select TWO.)

Accepted Answer

Configure the ECS service to place tasks in multiple Availability Zones.. Option A (multi-AZ task placement) and Option D (circuit breaker pattern) are correct. Multi-AZ placement spreads tasks across Availability Zones to tolerate AZ failures. Circuit breaker pattern prevents cascading failures. Option B is wrong because increasing memory does not improve resilience. Option C is wrong because using the same subnet reduces resilience. Option E is wrong because scheduled scaling does not handle unexpected spikes.

Answer

Use a single subnet for all tasks to simplify networking.

Answer

Increase the task memory reservation to handle peak load.

Answer

Use scheduled scaling to adjust task count based on historical patterns.

Question 4

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 5

Which TWO actions can help ensure that an application running on EC2 instances can survive the loss of an entire Availability Zone?

Accepted Answer

Use an Auto Scaling group with multiple Availability Zones. Deploying instances in multiple AZs ensures that if one AZ fails, instances in other AZs continue to run. Using an Auto Scaling group with multiple AZs automatically distributes instances and replaces failed ones. Option B is wrong because a single AZ is vulnerable. Option D is wrong because instance type does not affect AZ resilience. Option E is wrong because CloudWatch alarms do not distribute instances.

Answer

Deploy all instances in a single Availability Zone for consistency

Answer

Use a larger instance type to handle more load

Answer

Use CloudWatch alarms to monitor instance health

Question 6

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 7

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 8

Which THREE components are required to implement a global application that can withstand the failure of an entire AWS Region? (Select THREE.)

Accepted Answer

Amazon CloudFront with multiple origins and origin failover.. Options A, C, and D are correct. Route 53 with health checks and failover routing provides DNS failover. DynamoDB Global Tables provide multi-region write capability. CloudFront provides edge caching and origin failover. Option B is wrong because a single ALB is regional. Option E is wrong because RDS Single-AZ is not resilient.

Answer

An Application Load Balancer in the primary Region.

Answer

Amazon RDS with a single-AZ deployment.

Question 9

A company runs a critical web application on EC2 instances behind an Application Load Balancer (ALB). The application stores session state in an Amazon DynamoDB table. During a recent traffic spike, users experienced session timeouts and the application became unavailable. Which design change would BEST improve resilience?

Accepted Answer

Enable DynamoDB global tables or use a Multi-AZ deployment for the table.. Option C is correct because using a Multi-AZ deployment for DynamoDB provides automatic failover and higher availability. Option A is wrong because increasing instance size does not address session state persistence. Option B is wrong because read replicas do not improve write availability. Option D is wrong because ElastiCache for Redis is not as resilient as DynamoDB Multi-AZ for session state.

Answer

Move session state to Amazon ElastiCache for Redis with cluster mode disabled.

Answer

Add a read replica to the DynamoDB table.

Answer

Increase the EC2 instance sizes to handle more traffic.

Question 10

A company runs a stateless web application on AWS Lambda behind an Application Load Balancer (ALB). During a deployment, the team updates the Lambda function to a new version. Some users report seeing the old version of the application for several minutes after the deployment. What is the MOST likely cause?

Accepted Answer

The ALB target group is still pointing to the old Lambda function version due to connection draining.. Option B is correct because ALB has a warm-up effect and may keep old connections alive, causing traffic to old Lambda versions if the alias is not updated atomically. Option A is wrong because Lambda versions are immutable. Option C is wrong because CloudFront caching is unrelated to ALB. Option D is wrong because Lambda@Edge is not involved in this setup.

Answer

The Lambda function versions are not immutable, causing a gradual rollout.

Answer

Lambda@Edge is overriding the function version at the edge locations.

Answer

Amazon CloudFront is caching the old response and has not been invalidated.

Question 11

A company is designing a disaster recovery strategy for its primary RDS for PostgreSQL database in us-east-1. The RTO is 15 minutes and RPO is 1 minute. Which solution meets these requirements?

Accepted Answer

Create a cross-Region read replica in the secondary Region and promote it during failover.. Option C is correct because a cross-Region read replica can be promoted to a primary instance quickly, meeting both RTO and RPO. Option A is wrong because manual snapshots have a higher RPO. Option B is wrong because Multi-AZ is only within a region. Option D is wrong because automated backups alone do not enable cross-Region failover.

Answer

Use AWS Backup to copy automated backups to the secondary Region every hour.

Answer

Deploy a Multi-AZ RDS instance and failover to the standby in the same region.

Answer

Take manual snapshots of the database every 5 minutes and copy them to the secondary Region.

Question 12

A company runs a microservices application on Amazon ECS with Fargate launch type. The application experiences intermittent failures when calling an external API. The errors are transient and usually resolve within a few seconds. How should the company improve resilience?

Accepted Answer

Implement retry logic with exponential backoff in the application code.. Option B is correct because implementing retry logic with exponential backoff handles transient failures gracefully. Option A is wrong because scaling up may not help with API failures. Option C is wrong because increasing timeouts could worsen latency. Option D is wrong because async processing adds complexity and does not directly address API failures.

Answer

Increase the timeout of the external API call to 60 seconds.

Answer

Increase the number of tasks in the ECS service to handle failures.

Answer

Use an Amazon SQS queue to decouple the API call from the application.

Question 13

A company uses AWS CloudFormation to deploy a multi-tier application. During an update, the stack fails and rolls back. The rollback also fails, leaving the stack in UPDATE_ROLLBACK_FAILED state. The operations team needs to resolve this with minimal disruption. What is the MOST efficient approach?

Accepted Answer

Use the 'ContinueUpdateRollback' API or AWS Management Console to retry the rollback.. Option A is correct because continuing the rollback can resolve the failure and bring the stack to a consistent state. Option B is wrong because deleting the stack would remove all resources. Option C is wrong because executing a change set on a failed stack is not possible. Option D is wrong because manual modification is error-prone and not recommended.

Answer

Manually modify the resources to match the previous stack state.

Answer

Delete the stack and recreate it from the original template.

Answer

Execute a change set to update the stack to the desired configuration.

Question 14

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 15

A company wants to ensure that its Amazon S3 bucket can withstand the loss of an entire AWS Availability Zone. Which configuration meets this requirement?

Accepted Answer

Use the S3 Standard storage class.. Option C is correct because S3 Standard storage class automatically replicates data across at least three AZs. Option A is wrong because versioning does not provide AZ resilience. Option B is wrong because cross-Region replication is for geographic resilience, not AZ. Option D is wrong because S3 One Zone-IA stores data in a single AZ.

Answer

Configure cross-Region replication to another bucket.

Answer

Enable S3 Versioning on the bucket.

Answer

Use the S3 One Zone-IA storage class.

Question 16

A company runs a stateful application on EC2 instances in an Auto Scaling group. The application stores state on local instance storage. During a scaling event, users lose session data. How can the company make the application resilient without modifying the application code?

Accepted Answer

Enable sticky sessions on the Application Load Balancer.. Option D is correct because using a sticky session (session affinity) on the ALB ensures users are routed to the same instance, preserving local state. Option A is wrong because larger instances do not prevent data loss on termination. Option B is wrong because EBS volumes persist but require reattachment. Option C is wrong because reducing cooldown does not preserve state.

Answer

Reduce the Auto Scaling group cooldown period.

Answer

Increase the instance size to reduce scaling events.

Answer

Use Elastic Block Store (EBS) volumes instead of instance store.

Question 17

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 18

A company uses Amazon Route 53 with a failover routing policy to direct traffic to an active and a standby endpoint. The health checks are configured to check the active endpoint every 10 seconds. During a recent outage, the failover took over 3 minutes to detect and switch. How can the company improve the failover time to under 1 minute?

Accepted Answer

Configure a Route 53 calculated health check that aggregates multiple fast health checks with a lower failure threshold.. Option D is correct because using a calculated health check with faster endpoint checks and a lower failure threshold can reduce detection time. Option A is wrong because reducing the health check interval to 5 seconds is not supported (minimum is 10 seconds). Option B is wrong because latency routing does not provide active/passive failover. Option C is wrong because adding more health checks does not reduce failover time.

Answer

Add additional health checks for the same endpoint.

Answer

Reduce the health check interval to 5 seconds.

Answer

Change the routing policy to latency based.

Question 19

A company runs a critical application on Amazon EC2 instances in an Auto Scaling group. To ensure high availability, the instances are deployed across three Availability Zones. Which additional step should the company take to protect against a regional failure?

Accepted Answer

Deploy the application in a second AWS Region and use Route 53 with failover routing.. Option B is correct because deploying resources in multiple AWS Regions protects against a regional outage. Option A is wrong because placing instances in the same AZ reduces resilience. Option C is wrong because increasing minimum instances does not protect against region failure. Option D is wrong because more instance types do not affect regional resilience.

Answer

Place all instances in a single Availability Zone to simplify management.

Answer

Use EC2 Dedicated Hosts to ensure capacity.

Answer

Increase the minimum size of the Auto Scaling group to 10 instances.

Question 20

A company is designing a highly available architecture for a web application using AWS services. The application must be resilient to the failure of an entire AWS Region. Which TWO strategies should the company implement? (Choose TWO.)

Accepted Answer

Deploy the application in multiple AWS Regions and use Route 53 with failover routing policy.. Option A is correct because deploying to multiple regions with Route 53 failover provides cross-region disaster recovery. Option D is correct because using Amazon RDS Multi-AZ with cross-Region read replicas or Aurora Global Database ensures database resilience across regions. Option B is wrong because CloudFront alone does not provide compute failover. Option C is wrong because S3 cross-Region replication is for data, not compute. Option E is wrong because single-region Auto Scaling does not protect against region failure.

Answer

Use Amazon CloudFront with multiple origins in the same region.

Answer

Enable S3 cross-Region replication for static assets.

Answer

Use Auto Scaling groups in a single region with multiple Availability Zones.