SOA-C02 Reliability and Business Continuity Practice Test 14 — 15 Questions

Question 1

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.)

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Set the 'Rollback on failure' option to 'Yes' in the stack update options.. Both options B and C are correct. Option B: Setting 'Rollback on failure' to 'Yes' ensures that if the update fails, CloudFormation automatically rolls back to the last known good state. Option C: Creating a change set before updating allows you to review the changes and ensure they are correct before executing the update, which is a best practice to avoid failures; it does not itself perform a rollback but helps prevent failures.

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 2

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).. Configuring the Application Load Balancer (ALB) health checks with a low threshold (e.g., 2 consecutive failures) and a short interval (e.g., 5 seconds) allows the ALB to quickly detect unhealthy EC2 instances and stop routing traffic to them. This reduces the time the application spends trying to serve requests through failing instances during an RDS failover, improving overall responsiveness.

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 3

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.. Cross-Region Replication (CRR) automatically replicates objects to a destination bucket in a different AWS Region. If the source bucket is accidentally deleted, the replicated data remains intact in the destination bucket, ensuring business continuity. CRR provides geographic redundancy and protects against region-wide failures or bucket-level deletion events. Enabling versioning is required to configure CRR, as CRR requires versioning to be enabled on both the source and destination buckets. Therefore, both actions work together to ensure data resilience against accidental bucket deletion.

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 4

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.. Reducing the lifecycle hook timeout to 120 seconds ensures the custom action completes and the instance proceeds to termination promptly. Keeping the ALB deregistration delay at 300 seconds provides sufficient time to drain in-flight requests after deregistration. This prevents the instance from remaining in the terminating:wait state while still receiving traffic, avoiding request errors.

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 5

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.. Distributing EC2 instances across both Availability Zones and enabling cross-zone load balancing on the ALB ensures that traffic is routed to healthy instances in any AZ, providing high availability for the application tier during an AZ failure without changing the database cluster. Option A is incorrect because Multi-AZ for Aurora is already inherent; increasing instance size does not improve resilience. Option B is incorrect because a cross-region read replica does not help with within-region AZ failures and adds cost and complexity. Option C is incorrect because creating a second VPC in another region with a separate cluster is expensive and unnecessary for an AZ-level failure.

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 6

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 requires additional KMS permissions to transition SSE-KMS encrypted objects.. The most likely cause is that the KMS key policy does not have the required permissions for S3 to perform lifecycle transitions on encrypted objects. When using SSE-KMS, S3 must decrypt objects to transition them to a different storage class, requiring kms:Decrypt and other permissions. If these are not granted, the transition will not occur. Lifecycle policies apply to all objects matching the filter, including existing ones. S3 Versioning does not prevent transitions, and default encryption does not overwrite lifecycle rules.

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 7

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.. Creating a custom CloudWatch metric for memory utilization (e.g., from the CloudWatch agent) and configuring an ECS service auto scaling with a step scaling policy that adds tasks when memory exceeds a threshold allows scaling out before tasks are OOM-killed. Option A is wrong because increasing the task memory limit does not prevent the leak; it only delays failure. Option B is wrong because CPU-based scaling does not address memory issues. Option C 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 8

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'.. 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 when MFA is not present. Option A is wrong because an Allow statement would not override a Deny; the issue is with the condition, not an Allow statement. Option C is wrong because the condition key should be 'aws:MultiFactorAuthPresent', not 'aws:MFAPresent'. Option D is wrong because the policy is attached directly to all users, so group membership is not relevant.

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 9

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.. Creating a CloudFront invalidation for the path '/*' removes all cached objects from edge locations, so subsequent requests fetch the latest content from S3. Option A is wrong because disabling and re-enabling the distribution causes downtime and is unnecessary. Option B is wrong because changing the default TTL to 0 only affects new objects; existing cached objects remain until TTL expires unless invalidated. Option D is wrong because S3 lifecycle policies do not affect CloudFront 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 10

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).. 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 11

A company runs a stateful web application on a single Amazon EC2 instance with an Elastic IP address. The SysOps administrator needs to increase availability so that if the instance fails, a new instance can be launched quickly with the same configuration and the same IP address. The administrator also needs to ensure data is not lost. Which solution meets these requirements with the least operational overhead?

Accepted Answer

Create an AMI from the instance, store data on an Amazon EFS file system, and use an Auto Scaling group with a lifecycle hook to associate the Elastic IP. It separates the stateful data (stored on Amazon EFS) from the compute instance, ensuring data persistence even if the instance fails. Creating an AMI from the instance captures the configuration, and an Auto Scaling group with a lifecycle hook can associate the Elastic IP to the new instance automatically, providing a quick failover with minimal operational overhead.

Answer

Use an Application Load Balancer with an Auto Scaling group and a launch configuration that includes the Elastic IP

Answer

Create a CloudFormation template that launches a new instance and associates the Elastic IP

Answer

Place the instance in an Auto Scaling group with a minimum of 1 and a maximum of 1, and set the health check to replace unhealthy instances

Question 12

A company runs a critical stateful web application on Amazon EC2 instances in a single AWS region. The application stores user session data in an Amazon ElastiCache for Redis cluster. The SysOps administrator must design a disaster recovery (DR) strategy that can survive a complete regional outage with a Recovery Point Objective (RPO) of 15 minutes and a Recovery Time Objective (RTO) of 1 hour. The application must be able to redirect users to the DR region with minimal manual effort. Which combination of actions meets these requirements?

Accepted Answer

Create a read replica of the ElastiCache Redis cluster in the DR region using the native cross-region replication feature. Use Route 53 with failover routing to point to the DR region ALB when the primary health check fails. Pre-configure EC2 instances in an Auto Scaling group in the DR region.. ElastiCache for Redis supports cross-region replication via a read replica in the DR region, which can keep session data synchronized with minimal lag, meeting the 15-minute RPO. Route 53 failover routing with health checks on the primary region's ALB automatically redirects traffic to the pre-configured DR region EC2 instances and ALB, achieving the 1-hour RTO with minimal manual effort. Pre-configuring the DR region with an Auto Scaling group ensures compute capacity is ready, while the read replica provides the required data availability.

Answer

Use Amazon Route 53 with weighted routing to distribute traffic between the two regions. Use a global DynamoDB table for session data, and launch EC2 instances in the DR region only when a failure is detected using AWS CloudFormation StackSets.

Answer

Use an Amazon CloudFront distribution with multiple origins (primary and DR). Enable session stickiness at the CloudFront level. Use EC2 instances in both regions behind separate ALBs. No special data replication is needed because sessions are stored in Redis.

Answer

Use EC2 instances with an Auto Scaling group in both regions. Schedule a Lambda function to take snapshots of the Redis cluster every 15 minutes and copy them to the DR region. Use Route 53 latency routing to direct users to the nearest region.

Question 13

A company runs a critical production database on Amazon RDS for MySQL with Multi-AZ deployment. The SysOps administrator needs to be automatically notified when a failover event occurs, and also capture the exact time and reason for the failover for compliance purposes. Which AWS service or feature should be used to capture the failover event details with the least operational overhead?

Accepted Answer

Create an Amazon CloudWatch Events rule that matches the 'RDS DB Instance Event' for 'failover' and sends the event to an Amazon SNS topic for notification and logging.. Amazon CloudWatch Events (now part of Amazon EventBridge) can match RDS DB Instance events, including 'failover', and route them to an SNS topic for notification and to CloudWatch Logs for logging. This approach requires no custom scripting or polling, providing the least operational overhead while capturing the exact time and reason for the failover directly from the RDS event stream.

Answer

Enable detailed monitoring on the RDS instance and stream the logs to Amazon CloudWatch Logs where a metric filter can detect failover patterns.

Answer

Configure AWS CloudTrail to log all RDS API calls and analyze the logs for the 'Failover' event type.

Answer

Use AWS Config to create a config rule that evaluates whether the 'DBInstanceStatus' changes to 'failover' and then trigger a remediation action.

Question 14

A company runs a critical web application on Amazon EC2 instances that are part of an Auto Scaling group. The application receives unpredictable traffic spikes. The SysOps administrator needs to ensure that when a scale-out event occurs, new instances are ready to serve traffic quickly to minimize latency spikes. Currently, the instance launch and configuration process (including software installs and cache warming) takes about 5 minutes. The administrator wants to reduce the time it takes for new instances to start serving traffic. Which combination of Auto Scaling features should be used?

Accepted Answer

Implement an Auto Scaling warm pool with a minimum number of pre-initialized instances in a 'Stopped' state. Configure the scaling policy to move instances from the warm pool to the Auto Scaling group when needed.. An Auto Scaling warm pool maintains a pool of pre-initialized instances in a 'Stopped' state that are fully configured (software installed, cache warmed) and ready to serve traffic. When a scale-out event occurs, instances from the warm pool are moved to the Auto Scaling group and transitioned to 'Running' state, bypassing the 5-minute launch and configuration delay, thereby minimizing latency spikes.

Answer

Use a launch template that includes a pre-warmed Amazon Machine Image (AMI) with all software pre-installed, and configure the Auto Scaling group to use a larger instance type to reduce initialization time.

Answer

Use scheduled scaling to predictively launch instances before the traffic spikes based on historical patterns.

Answer

Configure lifecycle hooks to add a wait time during instance launch so that the instance is fully configured before it is placed behind the load balancer.

Question 15

A company runs a stateful web application on a single Amazon EC2 instance. The SysOps administrator needs to implement a high availability architecture that can tolerate an Availability Zone (AZ) failure. The application stores session state in memory and also writes critical data to an Amazon EBS volume. The administrator wants to use an Auto Scaling group and an Application Load Balancer (ALB). Which combination of steps is required to make the application highly available?

Accepted Answer

Migrate session state to Amazon ElastiCache for Redis, store critical data in Amazon EFS, create an Auto Scaling group across multiple AZs, and place it behind an ALB.. It addresses both the stateless requirement for horizontal scaling and the persistence of critical data across AZ failures. Migrating session state to ElastiCache for Redis removes the dependency on local instance memory, allowing any instance to handle any request. Storing critical data on Amazon EFS provides a shared, NFS-based file system that is accessible from all instances across multiple AZs, unlike EBS which is tied to a single AZ. Combining these with a multi-AZ Auto Scaling group and an ALB ensures the application can survive an entire AZ outage.

Answer

Create an Auto Scaling group that spans at least two Availability Zones, attach the existing EBS volume to the new instances, and use an ALB to distribute traffic.

Answer

Place the EC2 instance in an Auto Scaling group with a minimum and maximum of 1 in the same AZ, and attach an Elastic IP to the instance.

Answer

Use an ALB with the existing single instance as the target, and enable cross-zone load balancing.