DOP-C02 Practice Exam 54 — 20 Questions

Question 1

A company runs a containerized application on Amazon ECS with Fargate launch type. The application experiences intermittent failures when the ECS service scheduler attempts to place tasks during a deployment. The DevOps engineer notices that tasks fail to start due to insufficient IP addresses in the VPC subnets. What is the MOST resilient solution to prevent this issue?

Accepted Answer

Configure the ECS service to use multiple subnets with larger CIDR blocks across multiple Availability Zones.. Option D is correct because using a larger CIDR block for subnets provides more IP addresses, and using multiple subnets across Availability Zones increases availability and capacity. Option A is wrong because increasing desired count does not solve IP shortage. Option B is wrong because ECS service-linked role does not affect IP allocation. Option C is wrong because VPC endpoints do not provide IP addresses for tasks.

Answer

Create an ECS service-linked role with permissions to allocate IPs.

Answer

Increase the desired task count in the ECS service to pre-warm IP addresses.

Answer

Use VPC endpoints for ECS to reduce IP usage.

Question 2

A company is running a production database on Amazon RDS for PostgreSQL with Multi-AZ deployment. The database experiences a failover due to an AZ outage. What happens to the existing database connections during the failover?

Accepted Answer

Existing connections are dropped, and applications must reconnect to the new primary using the same endpoint.. Option C is correct. During a Multi-AZ failover, RDS automatically updates the DNS record to point to the standby, but existing connections to the primary are dropped and must be re-established. Option A is wrong because connections are not preserved. Option B is wrong because Multi-AZ automatically fails over without manual promotion. Option D is wrong because the CNAME record does not change; it's a DNS update.

Answer

Existing connections are automatically redirected to the standby without interruption.

Answer

The RDS endpoint IP address changes, and the application must update its configuration.

Answer

The primary DB instance is promoted to standby and connections remain active.

Question 3

An AWS account owner (Account A) owns an S3 bucket named my-bucket. The bucket policy shown in the exhibit is attached to the bucket. A user from Account B attempts to upload an object to the bucket without specifying the x-amz-acl header. What will happen?

Accepted Answer

The upload fails because the bucket policy requires the x-amz-acl header to be set to bucket-owner-full-control.. Option D is correct. The condition requires the x-amz-acl header to be set to bucket-owner-full-control. If the header is not specified, the condition fails, and the request is denied. Option A is wrong because the condition is not met. Option B is wrong because the policy does not grant permission without the header. Option C is wrong because the bucket policy evaluates before the object ACL.

Answer

The upload fails because the bucket policy requires the object ACL to be set, but the default ACL allows the upload anyway.

Answer

The upload succeeds because the bucket policy does not explicitly deny the request.

Answer

The upload succeeds because the bucket policy allows s3:PutObject for any principal.

Question 4

A company runs a stateful application on EC2 instances. The application stores session data locally. The instances are behind an ALB with sticky sessions enabled. A scaling event terminates an instance, causing loss of session data. How can the company prevent this while maintaining performance?

Accepted Answer

Use Amazon ElastiCache to store session data. Using ElastiCache for session storage externalizes session data, making it resilient to instance termination.

Answer

Use a dedicated EC2 instance for sessions

Answer

Disable sticky sessions

Answer

Increase the sticky session duration

Question 5

A DevOps engineer is designing a highly available web application using Amazon Route 53. The application is deployed in two AWS Regions. The engineer wants to route traffic to the nearest healthy endpoint. Which routing policy should be used?

Accepted Answer

Latency routing. Option B is correct because latency-based routing routes to the region with the lowest latency. Option A is wrong because geolocation routes based on geographic location, not latency. Option C is wrong because failover is for active-passive setup. Option D is wrong because weighted routing distributes traffic by weight.

Answer

Failover routing

Answer

Weighted routing

Answer

Geolocation routing

Question 6

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 7

A company uses AWS CloudFormation to deploy infrastructure. They want to ensure that if a stack update fails, the stack is automatically rolled back to the last known good state. However, they also want to preserve any resources that were created successfully before the failure. Which CloudFormation stack policy should be used?

Accepted Answer

Use a stack policy that denies update actions on resources that should be preserved.. Option C is correct because setting a stack policy that denies updates on specific resources can protect those resources during rollback. Option A is wrong because RollbackConfiguration is not a stack policy. Option B is wrong because stack policies define allowed actions, not rollback behavior. Option D is wrong because stack policies are not tied to creation time.

Answer

Define a creation policy with a resource signal.

Answer

Use a stack policy that allows all actions except delete.

Answer

Set the RollbackConfiguration property with a monitoring time.

Question 8

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 9

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 10

An organization runs a critical application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer. The application requires that all traffic be encrypted in transit. The security team mandates the use of TLS 1.2 or higher and specific ciphers. What is the MOST efficient way to enforce this requirement?

Accepted Answer

Configure the ALB with a security policy that enforces TLS 1.2 and the required ciphers.. Option A is correct because ALB supports a predefined security policy that can be set to require TLS 1.2 and specific ciphers. Option B is wrong because CloudFront is for CDN, not for backend ALB. Option C is wrong because NLB does not support TLS termination at the load balancer. Option D is wrong because configuring each EC2 instance is inefficient and not centralized.

Answer

Use a Network Load Balancer with TLS listeners and target groups.

Answer

Place a CloudFront distribution in front of the ALB and configure the origin protocol policy.

Answer

Install a self-signed certificate on each EC2 instance and configure the web server.

Question 11

A company is designing a highly available architecture for a web application. The application runs on Amazon EC2 instances in an Auto Scaling group across three Availability Zones. The instances are behind an Application Load Balancer (ALB). Which additional step should the team take to ensure that traffic is evenly distributed across all healthy instances in all Availability Zones?

Accepted Answer

Enable cross-zone load balancing on the ALB.. Option C is correct. By default, ALB distributes traffic evenly across AZs, but cross-zone load balancing must be enabled to distribute traffic evenly across all instances regardless of AZ. Option A is wrong because ALB already distributes traffic across AZs. Option B is wrong because Route 53 is not needed for internal distribution. Option D is wrong because target group health checks are already enabled.

Answer

Use Amazon Route 53 weighted routing policy to distribute traffic to each AZ.

Answer

Configure health checks on the target group to mark instances as unhealthy if they are in an AZ with fewer instances.

Answer

Configure the ALB to use least outstanding requests routing algorithm.

Question 12

A DevOps engineer runs the above command and sees that one target is unhealthy with reason 'Target.Timeout'. The target is an EC2 instance running a web server on port 80. The security group for the instance allows inbound traffic on port 80 from the ALB's security group. What is the most likely cause of the health check failure?

Accepted Answer

The web server on the instance is not responding to health check requests on port 80.. Option B is correct. The 'Target.Timeout' reason indicates that the health check request timed out, meaning the instance is not responding within the timeout period. The most common cause is that the web server is not running or is not listening on the correct port. Option A is wrong because the security group already allows traffic from the ALB. Option C is wrong because the health check is from the ALB, not the internet. Option D is wrong because the health check is to the instance's IP, not a public IP.

Answer

The instance does not have a public IP address.

Answer

The instance's network ACL is blocking inbound traffic from the internet.

Answer

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

Question 13

A company runs a web application on EC2 instances behind an ALB. To improve resilience, they want to automatically replace failed instances and maintain a minimum number of instances. Which AWS service should be used?

Accepted Answer

Amazon EC2 Auto Scaling. Auto Scaling is designed to automatically replace failed instances and maintain a desired capacity, improving resilience.

Answer

AWS CloudFormation

Answer

AWS Elastic Beanstalk

Answer

AWS Systems Manager

Question 14

A company wants to automatically recover an Amazon RDS DB instance if the underlying hardware fails. Which feature should the DevOps engineer enable?

Accepted Answer

Multi-AZ deployment.. Option B is correct because Multi-AZ deployment provides automatic failover to a standby in a different AZ. Option A is wrong because automated backups are for point-in-time recovery, not hardware failure. Option C is wrong because read replicas are for read scaling, not automatic failover. Option D is wrong because deletion protection prevents accidental deletion, not recovery.

Answer

Deletion protection.

Answer

Read replicas in a different Region.

Answer

Automated backups with a retention period of 35 days.

Question 15

A company is running a stateful web application on Amazon EC2 instances. The application stores session data locally on the instance. The company wants to make the application stateless and improve resilience. The DevOps team decides to use Amazon ElastiCache for Redis to store session data. What additional step should the team take to ensure that the session data is highly available?

Accepted Answer

Enable ElastiCache for Redis cluster mode with automatic failover across multiple Availability Zones.. Option B is correct. Enabling ElastiCache for Redis cluster mode with automatic failover ensures that if the primary node fails, a read replica is promoted, providing high availability. Option A is wrong because Multi-AZ for ElastiCache is for replication groups, not cluster mode. Option C is wrong because backing up to S3 does not provide automatic failover. Option D is wrong because manually promoting a replica is not automatic.

Answer

Deploy ElastiCache for Redis in a Multi-AZ configuration with automatic failover.

Answer

Use a single ElastiCache for Redis node and rely on the application to reconnect if the node fails.

Answer

Configure ElastiCache for Redis to back up session data to Amazon S3 every 5 minutes.

Question 16

A DevOps team uses the above CloudFormation template to create an S3 bucket. What does the bucket policy accomplish?

Accepted Answer

It denies all S3 operations on the bucket unless the request uses HTTPS.. Option B is correct. The policy denies all S3 actions on the bucket objects if the request is not sent over HTTPS (SecureTransport false). This enforces encryption in transit. Option A is wrong because it denies all actions, not just read. Option C is wrong because it denies only when not using HTTPS. Option D is wrong because the policy denies all actions, not just delete.

Answer

It denies all read access to the bucket for anonymous users.

Answer

It prevents anyone from deleting objects in the bucket.

Answer

It allows only HTTPS requests to the bucket and denies all HTTP requests.

Question 17

A company's production database on Amazon RDS Multi-AZ DB instance experienced a failover. The application experienced a brief outage. How can the company reduce the failover time?

Accepted Answer

Use Amazon RDS Proxy. Using RDS Proxy reduces failover time by maintaining connections and routing them to the new primary instance quickly.

Answer

Switch to a Single-AZ deployment

Answer

Increase the DB instance size

Answer

Enable Enhanced Monitoring

Question 18

A company is designing a resilient architecture for a critical application. Which TWO strategies improve resilience?

Accepted Answer

Deploy resources across multiple Availability Zones. Multi-AZ deployments and health checks with auto-remediation improve resilience by handling failures automatically.

Answer

Use a single large instance instead of multiple smaller ones

Answer

Disable automated backups to reduce latency

Answer

Deploy resources in a single Availability Zone

Question 19

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 20

Which THREE strategies can improve the resilience of an Amazon RDS for PostgreSQL database?

Accepted Answer

Enable automated backups with a retention period. Multi-AZ deployment provides automatic failover. Automated backups allow point-in-time recovery. Read replicas in other AZs provide read scalability and can be promoted in a disaster. Option B is wrong because a single-AZ is not resilient. Option E is wrong because disabling backups prevents recovery.

Answer

Disable automated backups to save costs

Answer

Use a single-AZ instance to reduce complexity