SOA-C02 Reliability and Business Continuity Practice Test 9 — 15 Questions

Question 1

A SysOps administrator receives an alert that an EC2 instance in an Auto Scaling group is unhealthy. The instance fails the EC2 status check. What is the BEST course of action to restore availability automatically?

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

Accepted Answer

Configure the Auto Scaling group to use EC2 status checks for health checks and set the health check grace period appropriately.. Configuring the Auto Scaling group to use EC2 status checks for health checks allows it to automatically detect when an instance fails the EC2 status check and replace it with a new one, ensuring high availability without manual intervention. The health check grace period prevents premature termination during initial instance bootstrapping. This is the most automated and resilient approach for restoring availability in response to EC2 status check failures.

Answer

Use AWS Systems Manager to replace the underlying host.

Answer

Manually reboot the instance from the EC2 console.

Answer

Create a CloudWatch alarm that triggers an SNS notification to the administrator.

Question 2

A company runs a web application on EC2 instances in an Auto Scaling group. The application is behind an Application Load Balancer. The company wants to ensure that the application can handle a sudden spike in traffic without downtime. What should the SysOps administrator do?

Accepted Answer

Configure a target tracking scaling policy based on average CPU utilization.. A target tracking scaling policy based on average CPU utilization allows the Auto Scaling group to automatically adjust capacity in response to real-time demand spikes. This dynamic scaling approach maintains a target metric (e.g., 50% CPU) by adding or removing instances, ensuring the application can handle sudden traffic bursts without downtime.

Answer

Use a scheduled scaling policy to add instances during business hours.

Answer

Reduce the number of Availability Zones to lower latency.

Answer

Manually increase the desired capacity of the Auto Scaling group when traffic increases.

Question 3

A company has a production RDS for MySQL database. The SysOps administrator receives an alert that the database instance is running out of storage. The company requires high availability and minimal downtime during any modifications. What should the administrator do?

Accepted Answer

Modify the RDS instance to increase the allocated storage. Since the instance is Multi-AZ, the modification will be applied with minimal downtime.. Modifying the allocated storage on a Multi-AZ RDS for MySQL instance can be done with minimal downtime. When you modify storage settings, Amazon RDS performs the update in the background, and for Multi-AZ deployments, the modification is applied to the standby first, then a failover occurs to minimize any interruption. This approach satisfies the high availability requirement and keeps downtime to a few seconds or less.

Answer

Add a read replica and use it for read traffic to reduce load on the primary.

Answer

Create a CloudWatch alarm to notify when storage is low, then manually clean up old data.

Answer

Create a new RDS instance with larger storage and migrate the data using AWS Database Migration Service.

Question 4

A company runs a stateless web application on EC2 instances in an Auto Scaling group. The application is deployed across multiple Availability Zones. The SysOps administrator wants to ensure that the application remains available even if an entire Availability Zone fails. What is the MOST effective way to achieve this?

Accepted Answer

Configure the Auto Scaling group to launch instances in at least two Availability Zones.. By configuring the Auto Scaling group to launch instances in at least two Availability Zones, the application can survive the failure of an entire AZ because the Auto Scaling group will automatically replace failed instances in the remaining healthy AZs. This design ensures that the stateless web application remains available as long as at least one AZ is operational, leveraging the fault isolation that AWS Availability Zones provide. The Auto Scaling group distributes instances across the specified AZs and will maintain the desired capacity even if one AZ becomes completely unavailable.

Answer

Create a CloudWatch alarm to reboot instances when they become unhealthy.

Answer

Use a single Availability Zone to reduce complexity.

Answer

Use a larger instance type to handle more traffic.

Question 5

A company runs a critical application on AWS Lambda functions. The functions are invoked by an API Gateway endpoint. The SysOps administrator needs to ensure that the application continues to work if an entire AWS Region becomes unavailable. What should the administrator do?

Accepted Answer

Deploy the same API Gateway and Lambda setup in a second Region and use Route 53 with failover routing.. Deploying the same API Gateway and Lambda setup in a second AWS Region and using Route 53 with failover routing creates an active-passive disaster recovery architecture. Route 53 health checks monitor the primary Region's endpoint, and if it becomes unhealthy (e.g., due to a regional outage), DNS failover automatically routes traffic to the secondary Region, ensuring continuous operation of the application.

Answer

Use AWS Global Accelerator to route traffic to the closest Region.

Answer

Configure Lambda functions with provisioned concurrency in multiple Regions.

Answer

Use Lambda@Edge to run the functions at edge locations.

Question 6

A company runs a web application on EC2 instances in an Auto Scaling group behind an ALB. The application uses an RDS MySQL database. The SysOps administrator needs to improve the reliability of the database layer. Which TWO actions should the administrator take? (Choose two.)

Accepted Answer

Enable Multi-AZ on the RDS instance.. Enabling Multi-AZ on an RDS MySQL instance automatically provisions and maintains a synchronous standby replica in a different Availability Zone. If the primary instance fails, Amazon RDS automatically fails over to the standby, providing high availability and improving database reliability without manual intervention. This directly addresses the need for a resilient database layer.

Answer

Take a manual snapshot every hour.

Answer

Create a read replica in a different Region.

Answer

Increase the DB instance class to the largest available.

Question 7

A company uses AWS CloudFormation to deploy infrastructure. The SysOps administrator needs to ensure that if a stack update fails, the stack is automatically rolled back to the last known good state. Which TWO steps should the administrator take? (Choose two.)

Accepted Answer

Configure the stack to use a service role with permissions to perform rollback actions.. A service role grants CloudFormation the necessary IAM permissions to perform rollback actions on resources, such as deleting or reverting changes, even if the user who initiated the update lacks those permissions. This ensures that the stack can automatically return to its last known good state without manual intervention. Option C is correct because rollback triggers allow monitoring CloudWatch metrics; if a metric breaches the specified threshold, CloudFormation automatically rolls back the stack, providing an additional safeguard. Option E is incorrect because a stack policy only prevents updates to protected resources but does not enable or automate rollback on failure.

Answer

Create a manual snapshot of the database before each update.

Answer

Enable termination protection on the stack.

Answer

Define a stack policy that prevents updates to the database resources.

Question 8

A company runs a critical application on EC2 instances in an Auto Scaling group. The group uses a dynamic scaling policy based on CPU utilization. The SysOps administrator wants to ensure that the application remains available during a planned maintenance event that will take down one of the Availability Zones. Which TWO actions should the administrator take? (Choose two.)

Accepted Answer

Update the Auto Scaling group to remove the affected Availability Zone from the list of enabled AZs.. Removing the affected Availability Zone from the Auto Scaling group prevents the group from launching new instances in a zone that will become unavailable during maintenance. This ensures that any new instances are launched only in the remaining healthy Availability Zones, maintaining application availability. Option C is correct because increasing the desired capacity temporarily compensates for the instances that will be terminated or become unreachable in the affected zone, ensuring the group has enough running instances to handle the load.

Answer

Manually terminate all instances in the affected Availability Zone.

Answer

Create a new launch configuration with a different AMI.

Answer

Disable the dynamic scaling policy to prevent scaling.

Question 9

A company runs a web application on EC2 instances behind an Application Load Balancer. The application stores session data in a DynamoDB table. To improve reliability, the SysOps administrator needs to ensure that session data is preserved if an EC2 instance fails. Which action should the administrator take?

Accepted Answer

Use DynamoDB to store session data, making it accessible from any instance.. The application already stores session data in DynamoDB, which is a fully managed, highly available, and durable database service. By using DynamoDB, session data is persisted independently of any single EC2 instance, so if an instance fails, another instance can retrieve the same session data from DynamoDB without loss. This design ensures session data is preserved and accessible from any healthy instance, meeting the reliability requirement.

Answer

Enable sticky sessions (session affinity) on the ALB.

Answer

Mount the same EBS volume to all EC2 instances to share session data.

Answer

Store session data in an ElastiCache Memcached cluster.

Question 10

A SysOps administrator is configuring an Amazon RDS for MySQL Multi-AZ deployment. What is the primary benefit of using Multi-AZ?

Accepted Answer

Automatic failover to a standby instance in a different Availability Zone.. In Amazon RDS for MySQL Multi-AZ deployments, the primary benefit is automatic failover to a standby instance in a different Availability Zone. This is achieved through synchronous replication to a standby in a separate AZ, ensuring that if the primary instance fails, RDS automatically promotes the standby to become the new primary, minimizing downtime and maintaining data durability.

Answer

Improved read performance by distributing queries across multiple instances.

Answer

Synchronous replication across AWS Regions.

Answer

Automatic creation of read replicas for disaster recovery.

Question 11

A company has a critical application running on EC2 instances in an Auto Scaling group behind an ALB. The application uses a custom health check endpoint at /health. The SysOps administrator notices that the ALB occasionally marks instances as unhealthy even though the application is running correctly. The health check settings are: HealthCheckIntervalSeconds=30, HealthyThresholdCount=5, UnhealthyThresholdCount=2. What is the most likely cause of the intermittent health check failures?

Accepted Answer

The HealthyThresholdCount is set too high, causing instances to remain unhealthy after transient issues.. With HealthyThresholdCount=5, an instance must pass five consecutive health checks to be marked healthy. After a transient failure, the instance requires five successful checks to become healthy again, which can cause prolonged unhealthy periods. Option A is incorrect because if the health check endpoint returns 5xx errors, the ALB would mark the instance as unhealthy; these errors are not ignored. Option B is incorrect because an UnhealthyThresholdCount of 2 is standard and does not cause intermittent failures. Option D is incorrect because using TCP instead of HTTP would not cause intermittent failures if the instance is reachable; the issue is related to the healthy threshold, not the protocol.

Answer

The health check endpoint returns 5xx errors, which are ignored by the ALB.

Answer

The UnhealthyThresholdCount is set too low.

Answer

The health check is using TCP instead of HTTP.

Question 12

A company uses Amazon S3 to store critical data. The SysOps administrator needs to protect against accidental deletion of objects. Which combination of actions should the administrator take? (Choose the best answer.)

Accepted Answer

Enable S3 Versioning and MFA Delete on the bucket.. Enabling S3 Versioning preserves all versions of an object, allowing recovery from accidental deletion or overwrite. MFA Delete adds an additional authentication layer, requiring multi-factor authentication to permanently delete object versions or suspend versioning, thus preventing unauthorized or accidental deletions.

Answer

Apply a bucket policy that denies s3:DeleteObject for all principals.

Answer

Set a lifecycle policy to expire objects after 30 days.

Answer

Configure cross-Region replication to a different bucket.

Question 13

A SysOps administrator is designing a disaster recovery plan for a web application that runs on EC2 instances with data stored in an RDS MySQL database. The application requires a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 1 hour. Which solution meets these requirements most cost-effectively?

Accepted Answer

Use RDS Multi-AZ with automated backups and EC2 AMI backups.. RDS Multi-AZ provides automatic synchronous replication to a standby instance in a different Availability Zone, ensuring minimal data loss and a fast failover that meets the 5-minute RPO and 1-hour RTO. Automated backups enable point-in-time recovery within the retention period, and EC2 AMI backups allow quick restoration of the application tier, making this the most cost-effective solution that satisfies both objectives without requiring cross-Region resources.

Answer

Use a single RDS instance with daily snapshots and EC2 instance store.

Answer

Use EC2 Auto Scaling across Regions with an RDS standby instance.

Answer

Use RDS Multi-AZ with read replicas in another Region.

Question 14

A company runs a stateful application on EC2 instances in an Auto Scaling group. The application maintains state in memory. The SysOps administrator wants to ensure that when an instance is terminated, the state is preserved and a new instance can resume operation. Which approach should the administrator use?

Accepted Answer

Use an Auto Scaling lifecycle hook to offload state before termination.. An Auto Scaling lifecycle hook can be configured to execute a custom action (e.g., offloading in-memory state to Amazon S3 or ElastiCache) before the instance is terminated. The lifecycle hook places the instance in a 'terminating:wait' state, allowing the administrator to run a script that preserves state, and then completes the termination via CompleteLifecycleAction. This ensures state is saved before the instance is fully terminated, enabling a new instance to resume operation.

Answer

Use a warm standby instance that takes over when the primary fails.

Answer

Configure the EC2 instance to run a script on shutdown to save state locally.

Answer

Enable connection draining on the ALB.

Question 15

A SysOps administrator is tuning the health check of an Auto Scaling group. The group uses an ALB. The application takes up to 2 minutes to start. The health check settings are: HealthCheckGracePeriod=300, HealthCheckType=EC2. The administrator notices that instances are often marked unhealthy and terminated shortly after launch. What should the administrator change?

Accepted Answer

Change the HealthCheckType to ELB.. Change the HealthCheckType to ELB. With EC2 type, the ASG only uses EC2 status checks and ignores the ALB health check, so ALB health check failures would not directly cause termination. Setting HealthCheckType=ELB makes the ASG use the ALB health check results, and the HealthCheckGracePeriod (300 seconds) then applies to those results, delaying termination until the application has time to start. Increasing the grace period (B) would not help because the ALB health check is not used when HealthCheckType=EC2; decreasing it (D) would make the problem worse. Option C is the correct answer.

Answer

Change the HealthCheckType to EC2 (already EC2, but change to ELB).

Answer

Increase the HealthCheckGracePeriod to 600 seconds.

Answer

Decrease the HealthCheckGracePeriod to 120 seconds.