SOA-C02 Reliability and Business Continuity Practice Test 16 — 15 Questions

Question 1

A company runs a web application on EC2 instances behind an Application Load Balancer (ALB) in a single Availability Zone. The application stores session data in an RDS MySQL DB instance. To improve reliability, the company wants to deploy the application across multiple Availability Zones. Which combination of actions should the company take to achieve this? (Choose the correct course of action.)

Accepted Answer

Deploy EC2 instances in two Availability Zones and place them behind an Application Load Balancer. Enable Multi-AZ for the RDS MySQL DB instance.. Option B is correct because deploying EC2 instances in multiple AZs behind an ALB and using Multi-AZ RDS improves availability and fault tolerance. Option A is wrong because a Network Load Balancer is not required for HTTP traffic. Option C is wrong because RDS replication alone does not distribute application traffic. Option D is wrong because RDS Read Replicas are for read scaling, not failover.

Answer

Deploy EC2 instances in a single Availability Zone behind an Application Load Balancer. Enable Multi-AZ for the RDS MySQL DB instance.

Answer

Deploy EC2 instances in two Availability Zones and place them behind a Network Load Balancer. Keep RDS MySQL as a single-AZ deployment.

Answer

Deploy EC2 instances in two Availability Zones. Configure an RDS MySQL Read Replica in a second Availability Zone and route read traffic to it.

Question 2

A SysOps administrator is tasked with ensuring that an Amazon S3 bucket can withstand the loss of an entire AWS Region. The bucket stores critical data that must be accessible with minimal latency from multiple regions. Which solution meets these requirements?

Accepted Answer

Configure S3 Cross-Region Replication to a bucket in another AWS Region. Use Amazon CloudFront with multiple origins pointing to both buckets.. Option C is correct because S3 Cross-Region Replication replicates objects to a bucket in another region, providing regional resilience, and using a CloudFront distribution with multiple origins can route requests to the nearest replica. Option A is wrong because versioning alone does not provide cross-region resilience. Option B is wrong because S3 Transfer Acceleration does not replicate data. Option D is wrong because MFA Delete does not provide geographic redundancy.

Answer

Enable S3 Versioning and configure a lifecycle policy to transition objects to S3 Glacier Deep Archive.

Answer

Enable S3 Versioning and MFA Delete on the bucket. Use S3 Object Lock to prevent object deletion.

Answer

Enable S3 Transfer Acceleration on the bucket and use a CloudFront distribution with the bucket as the origin.

Question 3

A company runs a stateful web application on EC2 instances in an Auto Scaling group across two Availability Zones. The application uses an Application Load Balancer for traffic distribution. Users report that their sessions are frequently lost during scale-in events. The SysOps administrator needs to minimize session loss without introducing significant latency. What should the administrator do?

Accepted Answer

Enable sticky sessions (session affinity) on the ALB. Configure a lifecycle hook on the Auto Scaling group with a wait time equal to the ALB's connection draining timeout.. Option C is correct because using an ALB with sticky sessions (session affinity) and a connection draining timeout that matches the lifecycle hook's wait time ensures that in-flight requests complete before instance termination. Option A is wrong because scaling based on memory does not address session stickiness. Option B is wrong because a larger cooldown delay helps but does not ensure session persistence across instances. Option D is wrong because a Network Load Balancer does not support sticky sessions by cookie in the same way and is not ideal for HTTP traffic.

Answer

Replace the Application Load Balancer with a Network Load Balancer. Enable proxy protocol v2 to pass client IP addresses.

Answer

Increase the Auto Scaling group's cooldown period to 600 seconds. Configure the ALB to have a deregistration delay of 600 seconds.

Answer

Configure the Auto Scaling group to scale based on memory utilization instead of CPU. Set the cooldown period to 300 seconds.

Question 4

A SysOps administrator is designing a disaster recovery plan for a critical application that runs on EC2 instances in a single region. The RTO is 1 hour, and the RPO is 15 minutes. The application data is stored on an Amazon EBS volume. Which approach meets these requirements at the lowest cost?

Accepted Answer

Take automated EBS snapshots every 15 minutes and copy them to the DR region. Use a pre-configured Amazon Machine Image (AMI) to launch EC2 instances from the latest snapshot.. Option B is correct because EBS Snapshots are incremental and can be copied to another region. Automating snapshot creation every 15 minutes meets the RPO, and restoring from a snapshot in the DR region can be done within an hour if the AMI is pre-staged. Option A is wrong because continuous replication can be expensive and may require additional infrastructure. Option C is wrong because RTO would likely exceed 1 hour due to full replication time. Option D is wrong because Multi-AZ does not protect against regional failure.

Answer

Deploy the application across multiple Availability Zones using an Auto Scaling group and an Application Load Balancer.

Answer

Use AWS Database Migration Service (DMS) for continuous replication to an EC2 instance in the DR region.

Answer

Use S3 Cross-Region Replication to replicate the EBS volume data to an S3 bucket in the DR region.

Question 5

A company is using AWS CloudFormation to manage infrastructure. They want to ensure that if a stack update fails, the stack automatically rolls back to the last known good state. Which two steps should the company take? (Choose TWO.)

Accepted Answer

Set the 'Rollback on failure' option to 'Yes' in the stack update options.. Option B and Option D are correct. Enabling rollback on failure (B) ensures automatic rollback if an update fails. Using a change set (D) allows reviewing changes before applying, reducing the risk of failure. Option A is wrong because deletion protection prevents accidental deletion, not rollback. Option C is wrong because SNS notifications do not trigger rollback. Option E is wrong because stack policies only protect resources from updates, not rollback.

Answer

Define a stack policy that prevents updates to critical resources.

Answer

Enable termination protection on the stack.

Answer

Configure an Amazon SNS topic to send notifications when the stack update fails.

Question 6

A company runs a web application on EC2 instances in an Auto Scaling group. The application uses an Amazon RDS Multi-AZ DB instance. The SysOps administrator notices that during a recent failover test, the application became unresponsive for several minutes. The administrator wants to improve the application's resilience during failover. Which three actions should the administrator take? (Choose THREE.)

Accepted Answer

Configure the Application Load Balancer health checks to have a low threshold (e.g., 2 consecutive failures) and a short interval (e.g., 5 seconds).. Options A, B, and D are correct. Using an RDS proxy (A) manages connections and reduces failover time. Retry logic (B) allows the application to reconnect after failover. Health checks with low thresholds (D) help the load balancer quickly detect and route away from unhealthy instances. Option C is wrong because synchronous replication is already used in Multi-AZ; asynchronous replication would reduce durability. Option E is wrong because increasing instance size does not reduce failover time.

Answer

Change the RDS DB instance to use asynchronous replication instead of synchronous replication.

Answer

Increase the EC2 instance size to handle more connections during failover.

Question 7

A company wants to ensure that its Amazon S3 data is resilient to an accidental deletion of an entire bucket. Which two actions should the company take? (Choose TWO.)

Accepted Answer

Configure Cross-Region Replication to replicate objects to a bucket in another AWS Region.. Options A and D are correct. Cross-Region Replication (A) copies objects to another bucket, ensuring data survives regional issues. S3 Versioning (D) allows recovery of deleted objects within the same bucket. Option B is wrong because MFA Delete requires multi-factor authentication to delete objects, but does not protect against bucket deletion. Option C is wrong because lifecycle policies delete objects, not protect them. Option E is wrong because Transfer Acceleration is for speed, not durability.

Answer

Configure a lifecycle policy to transition objects to S3 Glacier after 30 days.

Answer

Enable MFA Delete on the bucket.

Answer

Enable S3 Transfer Acceleration on the bucket.

Question 8

A company runs a critical application on a fleet of EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB). The application uses an Amazon RDS MySQL Multi-AZ DB instance for persistent storage. The SysOps administrator recently configured a lifecycle hook on the Auto Scaling group to perform a custom action before instance termination. During a recent scale-in event, the administrator noticed that some requests were still being routed to the terminating instance, causing errors. The ALB's deregistration delay is set to 300 seconds. The lifecycle hook has a default timeout of 3600 seconds. The administrator wants to ensure that the instance completes its custom action and that all in-flight requests are drained before the instance is terminated. The custom action typically takes 120 seconds. What should the administrator do to resolve this issue?

Accepted Answer

Reduce the lifecycle hook timeout to 120 seconds. Keep the deregistration delay at 300 seconds.. Option A is correct because reducing the lifecycle hook timeout to match the custom action duration (120 seconds) and keeping the deregistration delay slightly higher (e.g., 300 seconds) ensures that the instance completes its custom action and then ALB finishes draining requests before the instance terminates. Option B is wrong because increasing the deregistration delay to 600 seconds would delay termination unnecessarily and might not align with the lifecycle hook. Option C is wrong because disabling the lifecycle hook removes the custom action. Option D is wrong because changing to 'Replace and terminate' lifecycle hook type would terminate the old instance before launching a new one, which could cause capacity issues.

Answer

Change the lifecycle hook to use the 'Replace and terminate' type instead of 'Terminate'.

Answer

Disable the lifecycle hook and rely solely on the ALB's deregistration delay to drain connections.

Answer

Increase the deregistration delay to 600 seconds. Keep the lifecycle hook timeout at 3600 seconds.

Question 9

A company has a production AWS account with a single VPC and multiple subnets across two Availability Zones. The company hosts a web application on EC2 instances in an Auto Scaling group. The application uses an Amazon Aurora MySQL database cluster with one writer and two reader instances in the same VPC. The SysOps administrator configured AWS CloudTrail to log API calls and Amazon CloudWatch alarms for operational monitoring. After a recent network partition event in one Availability Zone, the application became unavailable for several minutes. The administrator wants to improve the application's resilience to such events without changing the database cluster configuration. The administrator has budget for additional resources but wants to minimize costs. What should the administrator do?

Accepted Answer

Ensure the Auto Scaling group launches instances in both Availability Zones. Configure the Application Load Balancer to be cross-zone load balancing enabled.. Option C is correct because distributing EC2 instances across multiple AZs and configuring the ALB as cross-zone enabled ensures that traffic is routed to healthy instances in any AZ. This provides high availability for the application tier without changing the database. Option A is wrong because adding a second VPC with its own database cluster would be expensive and complex. Option B is wrong because creating a read replica in another region does not help with AZ failure within the same region. Option D is wrong because Multi-AZ for Aurora is already inherent; the database cluster already has instances in multiple AZs by design.

Answer

Enable Multi-AZ for the Aurora cluster, which is already enabled by default. Additionally, increase the instance size of the writer instance.

Answer

Configure a cross-region read replica for the Aurora cluster and promote it to primary if the primary AZ fails.

Answer

Create a second VPC in a different AWS Region and set up a second Aurora cluster. Use Route 53 with failover routing to direct traffic to the secondary region if the primary fails.

Question 10

A company uses Amazon S3 to store sensitive financial documents. The company's compliance team requires that all objects be encrypted at rest using server-side encryption with AWS KMS managed keys (SSE-KMS). Additionally, the compliance team requires that if an object is not accessed for 90 days, it should be automatically moved to Amazon S3 Glacier to reduce costs. The SysOps administrator is tasked with implementing these requirements. The administrator creates an S3 bucket and enables default encryption with SSE-KMS. Then, the administrator creates a lifecycle policy with a transition action to Glacier after 90 days. During testing, the administrator notices that objects uploaded to the bucket are not being transitioned to Glacier after 90 days. What is the most likely cause of this issue?

Accepted Answer

The lifecycle policy was created after the test objects were uploaded, and the policy does not apply to existing objects.. Option D is correct because lifecycle policies only apply to objects that are uploaded after the policy is created, unless the policy is applied to the entire bucket and includes existing objects. If the lifecycle policy was created after the test objects were uploaded, those objects are not affected unless the policy is configured to cover existing objects. Option A is wrong because SSE-KMS does not prevent lifecycle transitions. Option B is wrong because S3 Versioning does not block transitions. Option C is wrong because S3 Object Lock can prevent deletion but not transitions to Glacier.

Answer

The bucket has S3 Versioning enabled, and the lifecycle policy does not apply to previous versions.

Answer

The bucket's default encryption setting overwrites the lifecycle policy.

Answer

The bucket has S3 Object Lock enabled, which prevents objects from being transitioned to Glacier.

Question 11

A company runs a containerized application on Amazon ECS with the Fargate launch type. The application is deployed across two Availability Zones and uses an Application Load Balancer (ALB) to distribute traffic. The application stores state in an Amazon ElastiCache Redis cluster. Recently, the development team deployed a new version of the application that introduced a memory leak. The leak causes the ECS tasks to consume more memory over time until they are OOM-killed. The SysOps administrator is asked to ensure that the application remains available and responsive. The administrator has configured an ECS service auto scaling based on average CPU utilization, but the memory leak causes tasks to fail before CPU utilization triggers scaling. Which action should the administrator take to automatically detect and replace failing tasks?

Accepted Answer

Create a custom CloudWatch metric for memory utilization and configure an ECS service auto scaling with a step scaling policy that adds tasks when memory exceeds a threshold.. Option B is correct because configuring an ECS service auto scaling with a step scaling policy based on a custom CloudWatch metric for memory utilization (e.g., from CloudWatch agent) allows scaling out before tasks are OOM-killed. Option A is wrong because increasing task memory limit does not prevent the leak; it only delays failure. Option C is wrong because using a target tracking policy based on CPU does not address memory issues. Option D is wrong because an ALB health check only detects HTTP failures, not memory exhaustion if the process is still responding.

Answer

Increase the task memory limit to the maximum allowed for the Fargate task size. This will prevent OOM-kills.

Answer

Configure an ECS service auto scaling with a target tracking policy based on average CPU utilization. Set the target value to 50%.

Answer

Configure the ALB health check to use a more sensitive path that fails when memory is low. The ECS service will automatically replace unhealthy tasks.

Question 12

A company has a production AWS account with multiple IAM users. The SysOps administrator needs to ensure that all IAM users have multi-factor authentication (MFA) enabled for console access. If a user does not have MFA enabled, they should be denied access to all AWS services except for the ability to enable MFA on their own account. The administrator has created an IAM policy that denies all actions if MFA is not present, but the policy is not working as expected; users without MFA can still access the S3 console. The administrator attaches the policy to all users. What is the most likely reason the policy is not effective?

Accepted Answer

The policy's condition is not properly configured to check for MFA. The condition should use 'aws:MultiFactorAuthPresent' with a value of 'false'.. Option B is correct because for the Deny effect to work, the condition must check for the presence of MFA. The condition key 'aws:MultiFactorAuthPresent' should be set to 'false' to deny access. If the condition is missing or incorrectly configured, the Deny statement does not apply. Option A is wrong because the policy needs to explicitly deny actions when MFA is not present; an Allow statement would not restrict. Option C is wrong because the policy should be attached to users or groups, not to all principals. Option D is wrong because the condition key is 'aws:MultiFactorAuthPresent', not 'aws:MFAPresent'.

Answer

The policy includes an Allow statement that grants access to all services, which overrides the Deny statement.

Answer

The policy uses the condition key 'aws:MFAPresent' instead of 'aws:MultiFactorAuthPresent'.

Answer

The policy is attached to an IAM group, but the users are not members of that group.

Question 13

A company runs a static website on Amazon S3 with a custom domain name (www.example.com). The website is accessed via Amazon CloudFront. The company's marketing team recently updated the website content, but users are reporting that they still see the old content. The SysOps administrator checks the S3 bucket and confirms that the new files are present. The administrator also checks CloudFront and finds that the default TTL for the cache behavior is 24 hours. The marketing team needs the new content to be visible immediately. What should the administrator do to make the new content available to users as quickly as possible?

Accepted Answer

Create a CloudFront invalidation for the path '/*' to remove all cached files.. Option A is correct because creating a CloudFront invalidation for the path '/*' removes all cached objects, so subsequent requests fetch the new content from the origin. Option B is wrong because disabling and re-enabling the distribution would cause downtime. Option C is wrong because changing the default TTL to 0 would require waiting for TTL to expire or invalidations. Option D is wrong because S3 lifecycle policies do not affect cache.

Answer

Disable the CloudFront distribution and re-enable it after 5 minutes.

Answer

Change the default TTL for the CloudFront cache behavior to 0 seconds.

Answer

Change the S3 bucket's lifecycle policy to expire objects after 1 day.

Question 14

A company runs a critical application on EC2 instances in an Auto Scaling group. The application processes messages from an Amazon SQS queue. The SysOps administrator notices that during periods of high load, the SQS queue depth increases significantly, and the application takes a long time to recover. The administrator wants to improve the application's ability to handle spikes in traffic without over-provisioning resources. The application is stateless and can scale horizontally. What should the administrator do?

Accepted Answer

Configure an auto scaling policy for the Auto Scaling group based on the SQS queue depth (ApproximateNumberOfMessagesVisible).. Option B is correct because configuring auto scaling based on the SQS queue depth (e.g., ApproximateNumberOfMessagesVisible) allows the Auto Scaling group to scale out proactively as the queue grows and scale in as it shrinks. Option A is wrong because increasing instance size (vertical scaling) is less elastic than horizontal scaling. Option C is wrong because using a larger instance type with more vCPUs still has limits. Option D is wrong because changing to a FIFO queue does not affect throughput scaling; FIFO queues have lower throughput.

Answer

Change the SQS queue from standard to FIFO to ensure messages are processed in order.

Answer

Use a larger EC2 instance type with enhanced networking to process messages faster.

Answer

Increase the EC2 instance size to a larger type with more CPU and memory.

Question 15

A company runs a production web application on AWS using Auto Scaling groups (ASGs) behind an Application Load Balancer (ALB). The application state is stored in an Amazon RDS for MySQL Multi-AZ DB instance. The application experiences periodic traffic spikes, and the current ASG uses a simple scaling policy based on average CPU utilization. Recently, during a spike, the application became unresponsive for several minutes. The CloudWatch metrics show that the CPU utilization on the RDS instance peaked at 80%, and the DB Connections metric reached the maximum allowed. The read replica lag increased to over 10 seconds during the spike. The web servers are stateless and scale out quickly. The operations team needs to improve the reliability and performance of the application to handle future spikes. Which solution should the team implement?

Accepted Answer

Increase the DB instance size to a larger instance class and implement an Amazon ElastiCache cluster to cache frequent database queries.. Option B is correct because increasing the DB instance size provides more CPU and memory capacity to handle the load, and caching with ElastiCache reduces read load on the database by serving frequent queries from cache. This directly addresses high CPU and connection limits on RDS, and reduces read replica lag. Option A is wrong because increasing ASG size and adding more read replicas may increase database load further due to more connections and replication overhead. Option C is wrong because switching to DynamoDB and Lambda would require significant application changes and DynamoDB may not be suitable for complex queries. Option D is wrong because reducing MaxConnections on RDS would make the problem worse, and modifying application code to reduce queries is not a quick fix.

Answer

Increase the desired capacity of the ASG and add more read replicas to distribute the database load.

Answer

Migrate the database to Amazon DynamoDB with auto scaling and rewrite the application to use a serverless architecture with AWS Lambda.

Answer

Reduce the maximum connections parameter on the RDS instance to prevent connection exhaustion and modify the application code to reduce the number of database queries.