SOA-C02 Reliability and Business Continuity Practice Test 8 — 15 Questions

Question 1

A company runs a critical web application on EC2 instances behind an Application Load Balancer in a single Availability Zone. To improve reliability, what is the MOST effective design change?

Accepted Answer

Launch EC2 instances across two or more Availability Zones.. The most effective design change to improve reliability is to launch EC2 instances across two or more Availability Zones. This eliminates the single point of failure at the Availability Zone level, ensuring that if one AZ experiences an outage, the Application Load Balancer can route traffic to healthy instances in another AZ. This directly addresses the core reliability principle of fault isolation and high availability.

Answer

Place the RDS database in a Multi-AZ deployment.

Answer

Add a second Application Load Balancer in the same Availability Zone.

Answer

Increase the EC2 instance size to handle more traffic.

Question 2

A company's S3 bucket contains critical data. The bucket policy accidentally allowed public write access, and a malicious actor uploaded several objects. The company needs to recover the bucket to a known good state as quickly as possible. What should the SysOps administrator do?

Accepted Answer

Use S3 Versioning to restore the bucket to a previous version.. Enabling S3 Versioning allows restoring a bucket to a previous state by deleting the current versions of objects, effectively rolling back to the last good version before the malicious uploads. Option A is incorrect because S3 Object Lock prevents deletion or overwrite for a specified retention period but does not provide version rollback. Option B is incorrect because MFA Delete requires additional authentication for delete operations but does not help restore previous versions. Option D is incorrect because S3 Cross-Region Replication replicates objects to another region but does not provide versioning or rollback capabilities.

Answer

Enable S3 Object Lock on the bucket to prevent further modifications.

Answer

Enable MFA Delete on the bucket to secure delete operations.

Answer

Configure S3 Cross-Region Replication to replicate data to another region.

Question 3

A SysOps administrator needs to ensure that an EC2 instance automatically recovers from an underlying hardware failure. Which action should be taken?

Accepted Answer

Create a CloudWatch alarm on the StatusCheckFailed metric and configure the recovery action.. A CloudWatch alarm on the StatusCheckFailed metric can be configured with the 'recover' action to automatically restart the EC2 instance on a new underlying host if a hardware failure is detected. This recovery action preserves the instance ID, private IP, Elastic IP, and instance metadata, ensuring minimal disruption. The StatusCheckFailed metric specifically monitors the instance's system status checks, which detect AWS hardware issues.

Answer

Launch a second instance in a different Availability Zone.

Answer

Assign an Elastic IP address to the instance.

Answer

Place the instance in an Auto Scaling group with a min size of 1.

Question 4

A company uses AWS Backup to back up its Amazon EFS file systems. The SysOps administrator needs to ensure that backups are retained for 7 years to meet compliance requirements. What should the administrator do?

Accepted Answer

Create a backup plan with a lifecycle policy that retains backups for 7 years.. AWS Backup allows you to define backup plans that include lifecycle policies to automatically transition backups to cold storage and expire them after a specified retention period. By setting the retention period to 7 years (2557 days) in the backup plan, AWS Backup will automatically manage the deletion of backups after that time, ensuring compliance without manual intervention.

Answer

Manually delete backups older than 7 years every month.

Answer

Increase the backup frequency to daily.

Answer

Configure cross-region backup to copy backups to another region.

Question 5

A SysOps administrator is designing a disaster recovery strategy for a production RDS MySQL database. The database must be recoverable within 15 minutes with a Recovery Point Objective (RPO) of less than 5 seconds. Which TWO actions should the administrator take? (Choose two.)

Accepted Answer

Enable Multi-AZ deployment for the RDS instance.. Multi-AZ deployment (Option B) provides automatic failover to a standby replica in a different Availability Zone, enabling recovery within minutes and meeting the 15-minute RTO. Cross-Region read replicas (Option C) allow asynchronous replication to another region with an RPO typically under 5 seconds, satisfying the RPO requirement. Together, they ensure both rapid failover and minimal data loss.

Answer

Create a read replica in the same AWS Region.

Answer

Enable automated backups with a retention period of 35 days.

Answer

Take manual snapshots every hour.

Question 6

A company runs a stateless web application on EC2 instances in an Auto Scaling group. To improve reliability during a traffic spike, which THREE actions should the SysOps administrator take? (Choose three.)

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 the number of EC2 instances in response to traffic spikes. This policy maintains the target metric (e.g., 50% CPU) by adding or removing instances, ensuring the application remains responsive without manual intervention. It is a key mechanism for improving reliability under variable load.

Answer

Enable detailed monitoring for EC2 instances.

Answer

Use a larger instance type to handle more traffic per instance.

Question 7

A company is designing a backup strategy for its Amazon S3 buckets. Which TWO methods can be used to protect against accidental deletion or overwriting of objects? (Choose two.)

Accepted Answer

Enable S3 Versioning on the bucket.. S3 Versioning preserves every version of an object, including overwrites and deletions. When versioning is enabled, a delete operation only adds a delete marker, and overwrites create a new version without removing the previous one. This allows recovery of previous object states at any time.

Answer

Enable MFA Delete on the bucket.

Answer

Configure S3 Cross-Region Replication.

Answer

Enable default encryption (SSE-S3) 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. The application is deployed in us-east-1 with instances in three Availability Zones. The company's disaster recovery plan requires failover to us-west-2 within 30 minutes with a Recovery Point Objective (RPO) of 15 minutes and a Recovery Time Objective (RTO) of 30 minutes. The application uses an RDS MySQL database and stores session data in ElastiCache Redis. The SysOps administrator has configured an RDS read replica in us-west-2 with cross-Region replication and an ElastiCache cluster in us-west-2. The administrator has also created an AMI of the EC2 instances and copied it to us-west-2. During a disaster simulation, the failover took 45 minutes because the application needed to repopulate the cache. What should the administrator do to meet the RTO? (Select TWO.)

Accepted Answer

Enable ElastiCache Global Datastore for Redis to replicate data across regions.. The 45-minute failover was due to the cold ElastiCache cluster in us-west-2 requiring application-level cache repopulation. To meet the 30-minute RTO, the cache must be warm at failover. Option A enables ElastiCache Global Datastore for Redis, which provides cross-Region replication with sub-minute RPO, keeping the us-west-2 cache synchronized in near real-time, eliminating the need for repopulation after failover. Option D (pre-warming via periodic export/import) is less reliable because it introduces a backup window, does not capture real-time changes, and may not guarantee cache freshness within the 15-minute RPO. Therefore, only Option A fully satisfies both RTO and RPO requirements.

Answer

Modify the application to store session data in the RDS database instead of ElastiCache.

Answer

Increase the size of EC2 instances in us-west-2 to handle the load faster.

Question 9

A company runs a web application on EC2 instances in an Auto Scaling group behind an Application Load Balancer. The application is deployed in a single Availability Zone. The SysOps administrator notices that during peak hours, the application becomes slow and some requests fail. CloudWatch metrics show that CPU utilization on the instances reaches 90%, but the Auto Scaling group does not scale out. The administrator has configured a target tracking scaling policy based on average CPU utilization with a target value of 75%. The Auto Scaling group has a minimum of 2, maximum of 10, and desired capacity of 2. What is the MOST likely reason the Auto Scaling group is not scaling out?

Accepted Answer

The Auto Scaling group is configured with a single Availability Zone, and the target tracking policy cannot scale out beyond the capacity of that single AZ.. The most likely reason is that the Auto Scaling group is configured with a single Availability Zone. Target tracking scaling policies operate within the constraints of the configured subnets. If the group is only in one AZ, the subnet may have insufficient IP addresses or the AZ may have reached its instance limit, preventing the group from scaling out beyond that AZ's capacity. Since the group has a maximum of 10, but the AZ capacity is limited, the scaling policy cannot add more instances. This is a common issue: AWS recommends using multiple Availability Zones for Auto Scaling groups to allow scaling across AZs and avoid single points of failure.

Answer

The target tracking policy uses a target value of 75%, but the average CPU is above that, so it should scale out.

Answer

The target tracking policy requires detailed monitoring to be enabled on the instances.

Answer

The Auto Scaling group has reached its maximum capacity of 10 instances.

Question 10

A company runs a stateless web application on EC2 instances in an Auto Scaling group. The application is deployed in us-east-1 with three Availability Zones. The SysOps administrator wants to ensure that the application remains available even if an entire Availability Zone becomes unavailable. The Auto Scaling group is configured with a minimum of 3, maximum of 9, and desired capacity of 3. The instances are distributed evenly across the three AZs. What additional configuration is required to ensure the application can survive an AZ failure?

Accepted Answer

Ensure the load balancer is cross-zone load balancing enabled and the Auto Scaling group has a sufficient maximum size to handle the load of a failed AZ.. With the Auto Scaling group already spanning three AZs and balanced, the key to surviving an AZ failure is ensuring the load balancer is configured to distribute traffic to healthy instances in the remaining AZs (e.g., cross-zone load balancing) and that the Auto Scaling group's maximum size is high enough to allow scaling up to replace lost capacity (e.g., max of 9 allows doubling capacity in remaining AZs). Option A is incorrect because simply increasing desired capacity to 6 does not guarantee distribution across AZs and does not address load balancing. Option C is incorrect because reducing to two AZs decreases fault tolerance. Option D is incorrect because placing in a single AZ removes all AZ-level redundancy.

Answer

Increase the desired capacity to 6 to ensure enough capacity if one AZ fails.

Answer

Configure the Auto Scaling group to launch instances in only two AZs to reduce costs.

Answer

Place the Auto Scaling group in a single AZ to simplify management.

Question 11

A company runs a production application on EC2 instances in an Auto Scaling group behind an Application Load Balancer. The application uses an RDS for PostgreSQL database. The SysOps administrator has configured a read replica in a different AWS Region for disaster recovery. During a disaster, the primary region becomes unavailable. The administrator promotes the read replica to a standalone instance. After promoting, the application fails to connect to the new database because the endpoint changed. The administrator needs to minimize downtime. What should the administrator do to handle the endpoint change automatically?

Accepted Answer

Use Amazon Route 53 with a weighted alias record that points to the primary database endpoint, and configure a health check to fail over to the secondary endpoint.. By using Amazon Route 53 with a weighted alias record that points to the primary database endpoint and configuring a health check, the administrator can automate DNS failover. When the primary region becomes unavailable, the health check fails, and Route 53 automatically routes traffic to the secondary record that points to the promoted read replica's endpoint. This minimizes downtime. Option A is wrong because Elastic IP addresses cannot be assigned to RDS instances; they are used for EC2 instances. Option C is wrong because manually updating application configuration files would increase downtime and is not automatic. Option D is wrong because an RDS proxy does not automatically update the endpoint after a disaster recovery promotion; it still requires the endpoint to be changed in the application configuration.

Answer

Assign an Elastic IP address to the RDS instance.

Answer

Update the application configuration files to point to the new endpoint.

Answer

Use an RDS proxy and configure it to automatically failover to the promoted replica.

Question 12

A company runs a web application on AWS that uses an Application Load Balancer (ALB) across multiple Availability Zones. The application is deployed on EC2 instances in an Auto Scaling group behind the ALB. The RDS database is Multi-AZ with synchronous replication. Recently, the operations team noticed that during a planned failover test of the primary RDS instance, the application experienced a 30-second timeout and returned 503 errors to users. The RDS failover completed successfully, but the application did not recover until the Auto Scaling group replaced all instances. The application health check endpoint on the EC2 instances checks database connectivity. The ALB health check is configured to check the health check endpoint every 10 seconds with a threshold of 2 consecutive failures. The application uses a connection pool with a timeout of 5 seconds. What is the MOST likely cause of the 503 errors and the need to replace instances?

Accepted Answer

The EC2 instances are caching the RDS DNS name, causing them to connect to the old primary endpoint after failover. The application health check fails, leading to instance replacement.. When RDS failover occurs, the DNS record for the primary instance is updated to point to the new primary. However, EC2 instances have DNS caching with TTL, so they continue using the old IP address. The application's health check tests database connectivity; since it cannot connect to the old primary (which is now a replica or offline), the health check fails. The ALB marks instances unhealthy after 2 consecutive failures (20 seconds), and the Auto Scaling group replaces them. New instances obtain the updated DNS record, restoring connectivity. Option A correctly identifies this DNS caching issue. Option B is incorrect because lowering the health check threshold would not prevent the initial failures; the issue is not the threshold but the inability to connect. Option C is incorrect because a 5-second connection pool timeout is reasonable for failover, but the real problem is DNS propagation, not timeout length. Option D is incorrect because a warm standby in another Region would not address DNS caching within the same Region.

Answer

The ALB health check threshold of 2 consecutive failures is too low, causing premature instance replacement.

Answer

The application connection pool timeout of 5 seconds is too short for RDS failover.

Answer

The Multi-AZ RDS configuration is insufficient; the company should implement a warm standby database in another Region.

Question 13

A company runs a critical web application on EC2 instances behind an Application Load Balancer (ALB) across three Availability Zones. The application stores session data in memory on the EC2 instances. During a deployment, a new version of the application is released by terminating and replacing instances. Users report that they are unexpectedly logged out during the deployment. What should a SysOps administrator do to improve the reliability of the application during deployments?

Accepted Answer

Use an ElastiCache cluster to store session state externally.. Storing session state externally in an ElastiCache cluster decouples session data from individual EC2 instances. When instances are terminated and replaced during deployment, the new instances can retrieve session state from the shared ElastiCache cluster, preventing users from being logged out. This approach ensures that session data persists independently of the EC2 instance lifecycle, maintaining application reliability during rolling updates.

Answer

Reduce the deployment to a single Availability Zone to minimize instance churn.

Answer

Store session data in an RDS Multi-AZ database.

Answer

Enable sticky sessions (session affinity) on the ALB.

Question 14

A company uses AWS CloudFormation to deploy a multi-tier application. The stack includes an RDS DB instance with automated backups enabled. The SysOps administrator needs to ensure that the database can be recovered to any point within the last 35 days with minimal data loss. What should the administrator do?

Accepted Answer

Set the backup retention period to 35 days.. Automated backups in RDS allow point-in-time recovery (PITR) to any second within the backup retention period. By setting the retention period to 35 days, the administrator enables recovery to any point within that window, minimizing data loss to the last committed transaction before the restore time.

Answer

Create a manual snapshot daily and retain 35 snapshots.

Answer

Enable Multi-AZ on the RDS instance.

Answer

Configure AWS Backup with a 35-day backup plan.

Question 15

A company runs a production workload on a fleet of EC2 instances in an Auto Scaling group (ASG). The ASG spans three Availability Zones. To avoid regional failure, the company wants to replicate the infrastructure in a second AWS Region and be able to fail over within 30 minutes. The application state is stored in an RDS MySQL database. What is the MOST cost-effective and reliable solution?

Accepted Answer

Create a cross-Region read replica of the RDS database. In the secondary Region, deploy a duplicate ASG and ALB. In a disaster, promote the read replica to a standalone instance and update Route 53 DNS.. It provides a cost-effective and reliable disaster recovery solution that meets the 30-minute failover requirement. A cross-Region read replica of RDS MySQL allows you to maintain an up-to-date copy of the database in the secondary Region with minimal cost (only paying for the replica instance and data transfer). In a disaster, you can promote the read replica to a standalone instance in minutes, and with a pre-deployed ASG and ALG in the secondary Region, you can update Route 53 DNS to redirect traffic, achieving failover within the required timeframe.

Answer

Use an Application Load Balancer with cross-Region load balancing to distribute traffic to both Regions.

Answer

Use RDS Multi-AZ in both Regions and configure synchronous replication between them.

Answer

Take daily snapshots of the RDS database and copy them to the secondary Region. In the event of a failure, restore the latest snapshot.