SOA-C02 Reliability and Business Continuity Practice Test 15 — 15 Questions

Question 1

A company runs a web application on EC2 instances in an Auto Scaling group behind an Application Load Balancer. The application stores session data on local instance storage. Users report that they are unexpectedly logged out during peak traffic. Which action should the SysOps Administrator take to improve reliability?

Accepted Answer

Configure an ElastiCache Redis cluster to store session state externally.. Option C is correct because storing session state in a shared Elasticache cluster provides a central, durable location that survives instance termination. Option A is wrong because it does not address session loss. Option B is wrong because instance store is ephemeral. Option D is wrong because it does not solve the session persistence issue.

Answer

Move the session storage to an instance store volume.

Answer

Enable sticky sessions on the Application Load Balancer.

Answer

Increase the size of the Auto Scaling group to handle peak traffic.

Question 2

A company uses AWS CloudFormation to deploy infrastructure. They want to ensure that if a stack update fails, the stack automatically rolls back to the last known good state. Which CloudFormation stack policy should be used?

Accepted Answer

Use the default 'Rollback on failure' setting.. Option A is correct because the 'Rollback on failure' setting (default behavior) causes CloudFormation to roll back failed stack updates. Option B is wrong because DisableRollback would leave the stack in a failed state. Option C is wrong because it is not a valid stack policy. Option D is wrong because it prevents stack updates, not rollback.

Answer

Enable termination protection on the stack.

Answer

Use a stack policy that prevents specific resources from being updated.

Answer

Set 'DisableRollback' to false.

Question 3

A company runs a critical database on an RDS for PostgreSQL instance in a single Availability Zone. The database experiences high write latency. The SysOps Administrator needs to improve the database's reliability and performance without downtime. Which solution meets these requirements?

Accepted Answer

Modify the RDS instance to be Multi-AZ with a standby in another Availability Zone.. Option B is correct because enabling Multi-AZ provides high availability with automatic failover, and it can be modified without downtime. Option A is wrong because converting to Multi-AZ in a single AZ does not improve performance. Option C is wrong because creating a read replica does not improve write performance. Option D is wrong because increasing storage size might help performance but does not improve reliability.

Answer

Create a Multi-AZ deployment in the same Availability Zone.

Answer

Increase the allocated storage for the RDS instance.

Answer

Create a read replica in another Availability Zone and redirect read traffic.

Question 4

A company uses Amazon S3 to store critical data. They need to protect against accidental deletion of objects. Which feature should the SysOps Administrator enable?

Accepted Answer

Enable versioning on the bucket.. Option C is correct because S3 Versioning allows you to recover from accidental deletions by preserving previous versions. Option A is wrong because MFA Delete adds an extra layer but is not sufficient alone. Option B is wrong because cross-region replication does not prevent deletion. Option D is wrong because lifecycle policies automate transitions, not protection.

Answer

Create a lifecycle policy to transition objects to Glacier.

Answer

Configure cross-region replication.

Answer

Enable MFA Delete on the bucket.

Question 5

An application running on EC2 instances in an Auto Scaling group uses an SQS queue for decoupling. The application experiences increased latency when the queue has a high number of messages. The SysOps Administrator needs to maintain responsiveness. Which solution is the most cost-effective?

Accepted Answer

Configure a CloudWatch alarm on the queue depth to trigger Auto Scaling policies.. Option D is correct because using CloudWatch alarms on the queue depth to trigger Auto Scaling policies automatically scales out when needed and scales in when not, balancing cost and responsiveness. Option A is wrong because it may be cost-inefficient. Option B is wrong because it does not change the number of consumers. Option C is wrong because increasing batch size may help but does not scale capacity.

Answer

Increase the desired capacity of the Auto Scaling group.

Answer

Use a larger instance type for the EC2 instances.

Answer

Increase the visibility timeout of the SQS queue.

Question 6

A company runs a stateful web application on a single EC2 instance. The SysOps Administrator wants to improve fault tolerance. Which design should they implement?

Accepted Answer

Place instances in an Auto Scaling group across two Availability Zones, use an Application Load Balancer, and store session state in ElastiCache.. Option A is correct because a Multi-AZ deployment with an ALB and Auto Scaling group distributes traffic across instances in multiple AZs, and using ElastiCache for session state provides fault tolerance. Option B is wrong because it still has a single point of failure. Option C is wrong because it lacks load balancing and auto scaling. Option D is wrong because it uses instance store for session state, which is ephemeral.

Answer

Create a Multi-AZ RDS instance and attach it to the existing EC2 instance.

Answer

Add a second EC2 instance in the same Availability Zone and use a Network Load Balancer.

Answer

Use an Auto Scaling group with a launch configuration that stores session data on instance store.

Question 7

A company wants to ensure that its S3 bucket is accessible only from a VPC. Which configuration should the SysOps Administrator implement?

Accepted Answer

Create an S3 VPC endpoint and attach a bucket policy that restricts access to that endpoint.. Option B is correct because S3 bucket policies can restrict access to a specific VPC or VPC endpoint. Option A is wrong because it does not restrict to a VPC. Option C is wrong because it grants public access. Option D is wrong because S3 does not support security group associations.

Answer

Configure a bucket policy that allows access from the public internet.

Answer

Make the bucket public and rely on IAM roles.

Answer

Attach a security group to the S3 bucket.

Question 8

A company is using AWS CloudFormation to manage its infrastructure. The SysOps Administrator needs to ensure that updates to a critical stack do not accidentally replace the database. Which feature should be used?

Accepted Answer

Define a stack policy that denies updates to the database resource.. Option C is correct because a stack policy can protect specific resources from being updated or replaced during a stack update. Option A is wrong because change sets allow preview but do not prevent replacement. Option B is wrong because it does not prevent updates. Option D is wrong because drift detection identifies changes but does not prevent them.

Answer

Use drift detection to identify changes.

Answer

Enable termination protection on the stack.

Answer

Use a change set to review the updates before executing them.

Question 9

A company runs a web application on EC2 instances in a private subnet. The application needs to connect to an RDS database in a different VPC. The VPCs are peered. The SysOps Administrator is troubleshooting connectivity issues. The RDS security group allows inbound traffic from the EC2 security group, but connections still fail. What could be the issue?

Accepted Answer

The route tables in each VPC do not have routes to the peered VPC CIDR.. Option A is correct because VPC peering does not support transitive routing, so the EC2 instance cannot access the RDS if it is in a different region or if the route tables are not configured properly. Option B is wrong because security groups are stateful. Option C is wrong because network ACLs must allow outbound traffic, but the error description suggests routing issue. Option D is wrong because DNS resolution is not needed for direct IP connectivity.

Answer

The RDS instance does not have public DNS resolution enabled.

Answer

The network ACL for the private subnet is blocking inbound traffic.

Answer

The security group outbound rules on the EC2 instance are blocking traffic.

Question 10

A company is designing a disaster recovery strategy for its primary AWS region. The application runs on EC2 instances with an RDS database. The RPO is 15 minutes and RTO is 2 hours. Which TWO actions should the SysOps Administrator take to meet these requirements? (Choose TWO.)

Accepted Answer

Configure RDS cross-region replication to a second region.. Option A is correct because RDS cross-region replication can achieve RPO of seconds to minutes. Option D is correct because using CloudFormation with a template stored in S3 allows quick provisioning of resources in the DR region, meeting RTO. Option B is wrong because AMIs are region-specific; they must be copied to the DR region. Option C is wrong because it does not meet RPO. Option E is wrong because manual snapshots cannot achieve 15-minute RPO.

Answer

Create AMIs of the EC2 instances and share them with the DR region.

Answer

Take manual RDS snapshots every 15 minutes and copy them to the DR region.

Answer

Use AWS Backup to copy backups to a second region daily.

Question 11

A company runs a stateless web application on EC2 instances behind an Application Load Balancer. The SysOps Administrator needs to ensure the application can withstand the loss of an entire Availability Zone. Which THREE steps should be taken? (Choose THREE.)

Accepted Answer

Configure the Auto Scaling group to launch instances in at least two Availability Zones.. Option A is correct because deploying across multiple AZs ensures that if one AZ fails, the application still runs. Option C is correct because ALB can distribute traffic to healthy instances in any AZ. Option D is correct because Auto Scaling across AZs replaces failed instances in other AZs. Option B is wrong because it would distribute traffic to one AZ at a time. Option E is wrong because EC2 is not zone-specific.

Answer

Enable cross-zone load balancing on the ALB.

Answer

Use an Elastic IP address for each EC2 instance.

Question 12

A company wants to ensure its SysOps Administrator can recover an EBS volume from a snapshot. Which TWO steps are required? (Choose TWO.)

Accepted Answer

Specify the Availability Zone when creating the volume.. Option A is correct because you must have a snapshot to create a volume. Option D is correct because when creating a volume from a snapshot, you must specify the Availability Zone. Option B is wrong because snapshots are already encrypted at rest. Option C is wrong because instance store volumes cannot be created from snapshots. Option E is wrong because KMS keys are optional for encryption.

Answer

Configure a KMS key for the snapshot.

Answer

Attach the volume to an EC2 instance.

Answer

Enable encryption on the snapshot.

Question 13

Refer to the exhibit. An IAM policy is attached to a group. A SysOps Administrator in that group tries to terminate an EC2 instance with the tag 'Environment=production'. The action fails. What is the most likely reason?

Accepted Answer

The instance does not have the tag 'Environment=production'.. Option A is correct because the policy allows termination only for instances with the tag 'Environment=production', but there might be an explicit deny elsewhere or the instance does not have the tag. Option B is wrong because the policy allows the action. Option C is wrong because the condition uses StringEquals, which is case-sensitive. Option D is wrong because the condition key is valid.

Answer

The condition key 'ec2:ResourceTag/Environment' is invalid.

Answer

The policy does not allow the ec2:TerminateInstances action.

Answer

The condition uses 'StringEquals' instead of 'StringLike'.

Question 14

A company runs a critical microservices application on Amazon ECS with Fargate launch type. The application consists of several services that communicate via internal HTTP calls. The SysOps Administrator notices that during periods of increased load, some services become unresponsive and the health checks fail. The ECS service auto scaling is configured based on CPU utilization, but it does not scale quickly enough. The administrator needs to improve the reliability and responsiveness of the application. The services are stateless and can be scaled horizontally. The current architecture uses a single Application Load Balancer for each service. The ALB health checks are set to a 30-second interval with a 5-second timeout and 2 unhealthy thresholds. The administrator has observed that when a service instance becomes unhealthy, it takes too long for the ALB to stop sending traffic to it, causing errors. What should the SysOps Administrator do to improve the reliability and responsiveness of the application?

Accepted Answer

Configure the ALB health check to have a 5-second interval, 2-second timeout, and 2 unhealthy threshold.. Option A is correct because reducing the health check interval and unhealthy threshold will detect failures faster and stop routing traffic sooner, improving responsiveness. Option B is wrong because increasing the interval and threshold would make detection slower. Option C is wrong because using a Network Load Balancer does not change health check behavior and may not support HTTP health checks. Option D is wrong because increasing CPU threshold delays scaling, which would worsen the problem.

Answer

Increase the ALB health check interval to 60 seconds and unhealthy threshold to 5.

Answer

Increase the ECS service auto scaling target CPU utilization to 90%.

Answer

Replace the ALB with a Network Load Balancer and use TCP health checks.

Question 15

A company runs a file-sharing application on AWS. Users upload files to an S3 bucket, which triggers a Lambda function to process the files and store metadata in a DynamoDB table. Recently, users have reported that some uploaded files are never processed. The SysOps Administrator checks the CloudWatch logs and finds no errors from the Lambda function. The S3 bucket is configured to send events to the Lambda function. The DynamoDB table has sufficient write capacity. The administrator suspects that the event notifications are being lost. Which action should the SysOps Administrator take to ensure that every file upload triggers a Lambda function and that the function processes the file successfully?

Accepted Answer

Configure an SQS queue as the event destination for the S3 bucket, and have the Lambda function process messages from the queue.. Option B is correct because enabling SQS as the event destination provides a durable queue that can retry failed deliveries. The Lambda function can poll the queue and process messages reliably. Option A is wrong because adding more Lambda concurrency does not solve event loss. Option C is wrong because DynamoDB Streams are not triggered by S3 events. Option D is wrong because increasing DynamoDB capacity does not address event notification issues.

Answer

Use DynamoDB Streams to capture file metadata changes instead of Lambda invocation.

Answer

Increase the Lambda function's reserved concurrency to handle more invocations.

Answer

Increase the write capacity of the DynamoDB table to avoid throttling.