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

Question 1

A company runs a critical web application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB). The application uses session stickiness (sticky sessions) to maintain user sessions. The SysOps administrator notices that when instances are replaced during a scale-in or failure event, users lose their session data. The administrator needs to preserve session data across instance failures without losing stickiness benefits. What should the administrator do?

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

Accepted Answer

Disable sticky sessions on the ALB and configure the application to store session data in an external session store like Amazon ElastiCache for Redis.. It eliminates the dependency on stickiness by storing session data externally in Amazon ElastiCache for Redis. This way, if an instance fails or is scaled in, any other instance can retrieve the session data from the shared cache, preserving the user session. Disabling sticky sessions is necessary because with external storage, stickiness is no longer needed and can cause uneven load distribution.

Answer

Increase the stickiness duration to a very high value so that sessions are not lost during brief interruptions.

Answer

Change the Auto Scaling group to use a larger instance type to handle more sessions per instance, reducing the likelihood of session loss.

Answer

Configure the Auto Scaling group to use a larger minimum size and a lower maximum, so instances are less likely to be terminated.

Question 2

A company runs a web application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB). The application stores session state in memory on each instance. The SysOps administrator wants to make the application highly available across multiple Availability Zones without losing session data when instances are terminated or replaced. The solution must minimize application changes. Which approach should the administrator take?

Accepted Answer

Store session data in a shared Amazon ElastiCache cluster and modify the application to read/write session state to ElastiCache.. Storing session state in a shared Amazon ElastiCache cluster decouples session data from individual EC2 instances, allowing any instance in the Auto Scaling group to serve any user request without losing session data when instances are terminated or replaced. This approach requires minimal application changes (only modifying the session handler to point to ElastiCache) and supports high availability across multiple Availability Zones by using a replicated ElastiCache cluster (e.g., Redis with replication).

Answer

Use sticky sessions (session affinity) on the ALB and configure the Auto Scaling group with a larger min size.

Answer

Deploy the application in multiple AWS Regions and use Amazon Route 53 with latency-based routing.

Answer

Store session data in an Amazon RDS for MySQL database and configure the application to read/write session state to the database.

Question 3

A company runs a critical database workload on an Amazon RDS for MySQL DB instance with Multi-AZ deployment in the us-east-1 region. The SysOps administrator must design a disaster recovery strategy that can recover from a complete regional outage. The Recovery Time Objective (RTO) is 2 hours and the Recovery Point Objective (RPO) is 1 hour. Which solution meets these requirements at the lowest cost?

Accepted Answer

Create a cross-Region read replica in another Region and promote it to a standalone DB instance during a disaster.. A cross-Region read replica continuously replicates data from the primary RDS MySQL instance to another Region with minimal lag, typically achieving an RPO of seconds to minutes, well within the 1-hour requirement. Promoting the replica to a standalone instance during a disaster can be done in minutes, meeting the 2-hour RTO. This approach is the lowest cost among the viable options as it uses existing replication infrastructure without additional data transfer fees for snapshots or DMS replication instances.

Answer

Create manual snapshots of the DB instance every hour and copy them to another AWS Region.

Answer

Enable automated backups with a retention period of 35 days and restore to a different Region when needed.

Answer

Use AWS Database Migration Service (DMS) to continuously replicate data to a DB instance in another Region.

Question 4

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

Accepted Answer

Use an Auto Scaling group across multiple AZs, migrate session storage to Amazon ElastiCache (multi-AZ), and migrate application data from EBS to Amazon EFS (file system mounted across AZs).. It addresses both session state and data durability across AZ failures. Migrating session storage to ElastiCache (multi-AZ) ensures session data survives instance failure, and migrating application data from EBS to EFS provides a shared, multi-AZ file system that persists independently of any single EC2 instance. This combination allows the Auto Scaling group to launch new instances in any AZ and immediately access both session and application data.

Answer

Create an AMI of the current instance, configure an Auto Scaling group with a launch template that uses the AMI, and attach the existing EBS volume to new instances.

Answer

Create a multi-AZ Auto Scaling group and use sticky sessions (session affinity) on the ALB to tie users to specific instances.

Answer

Use an Auto Scaling group in a single AZ and use a Multi-AZ RDS instance for data storage.

Question 5

A company runs a global e-commerce application that uses Amazon DynamoDB as its primary database. The application requires single-digit millisecond read and write latency from any region and must continue to operate during a regional outage with minimal data loss. Which DynamoDB feature should the SysOps administrator enable to meet these requirements?

Accepted Answer

DynamoDB global tables. DynamoDB global tables provide multi-Region, multi-active replication, enabling single-digit millisecond reads and writes from any Region while offering automatic failover and recovery during a regional outage. This feature uses DynamoDB Streams to replicate data across Regions with eventual consistency, meeting the requirement for continued operation with minimal data loss.

Answer

DynamoDB Accelerator (DAX)

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DynamoDB Point-in-Time Recovery (PITR)

Answer

DynamoDB Auto Scaling

Question 6

A company runs a critical MySQL database on an Amazon RDS DB instance in a single Availability Zone. The SysOps administrator needs to implement a disaster recovery solution with a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 1 hour, while minimizing costs. Which solution meets these requirements?

Accepted Answer

Enable cross-Region automated backups to another Region. Cross-Region automated backups replicate transaction logs to another AWS Region with a typical lag of a few minutes, enabling point-in-time recovery (PITR) that can meet an RPO of 5 minutes. When a disaster occurs, you can restore the automated backup to a new DB instance in the destination Region, and the RTO depends on the restore time, which can be under 1 hour for a properly sized instance. This solution minimizes costs by avoiding the continuous compute and storage overhead of a standby replica or read replica.

Answer

Enable Multi-AZ deployment with a synchronous standby replica in another Availability Zone

Answer

Create a cross-Region read replica and promote it to a standalone DB instance during a disaster

Answer

Take daily automated snapshots and copy them to another Region manually

Question 7

A company runs a critical application on Amazon EC2 instances across multiple Availability Zones. The application stores state data on a shared Amazon EFS file system. The SysOps administrator needs to ensure that the file system remains available if an entire Availability Zone fails. The file system must also provide low-latency access from all instances. Which configuration meets these requirements?

Accepted Answer

Create an EFS file system with the Standard storage class in the same Region, and mount it from all instances using the regional mount target.. The EFS Standard storage class stores data redundantly across multiple Availability Zones (AZs) within a Region, ensuring high availability and durability even if an entire AZ fails. By mounting the file system using the regional mount target (which resolves to the EFS file system's regional DNS name), instances in any AZ can access the file system with low latency, as EFS automatically routes traffic to the most appropriate mount target in the same AZ. This configuration meets both the availability and low-latency requirements without additional replication or failover complexity.

Answer

Create an EFS file system with the One Zone storage class and mount it from all instances.

Answer

Create an EFS file system with the Standard storage class, enable replication to another Region, and use DNS failover.

Answer

Create an EFS file system with the Standard storage class, and enable Multi-AZ deployment.

Question 8

A company hosts a critical web application on Amazon EC2 instances in a single AWS Region (us-east-1). The SysOps administrator needs to implement a Disaster Recovery (DR) solution using a different AWS Region (us-west-2). The DR plan requires a Recovery Time Objective (RTO) of 1 hour and a Recovery Point Objective (RPO) of 15 minutes. The application uses an Amazon Aurora MySQL DB cluster and static assets stored in an Amazon S3 bucket. Which combination of actions should the administrator take to meet these requirements?

Accepted Answer

Create an Aurora cross-Region read replica in us-west-2. Configure S3 Cross-Region Replication from the source bucket to a destination bucket in us-west-2. During DR, promote the read replica to a primary cluster and update DNS.. Aurora cross-Region read replicas provide asynchronous replication with an RPO typically under 1 second, easily meeting the 15-minute RPO requirement. Promoting the read replica to a primary cluster in us-west-2 can be completed within minutes, satisfying the 1-hour RTO. S3 Cross-Region Replication (CRR) automatically replicates static assets to the destination bucket in us-west-2 with near-real-time latency, ensuring the S3 data is also current within the RPO window.

Answer

Take a manual snapshot of the Aurora DB cluster every 15 minutes and copy it to us-west-2. Use S3 batch operations to copy assets to us-west-2 daily.

Answer

Enable Aurora Multi-AZ in us-east-1 and configure S3 transfer acceleration to us-west-2.

Answer

Use AWS Database Migration Service (DMS) for continuous replication to a DB instance in us-west-2. Use S3 versioning to keep previous object versions.

Question 9

A company runs a web application on Amazon EC2 instances in an Auto Scaling group that spans two Availability Zones. The application uses an Application Load Balancer (ALB) that is deployed across the same Availability Zones. The SysOps administrator wants to ensure the application remains available if an entire Availability Zone fails. Which configuration is essential for this high availability?

Accepted Answer

Configure the Auto Scaling group with at least one instance in each Availability Zone.. For high availability across an Availability Zone (AZ) failure, the Auto Scaling group must have at least one healthy instance in each AZ. This ensures that if one AZ becomes unavailable, the ALB can route traffic to instances in the remaining AZ. Without this minimum distribution, a single AZ failure could leave the application with zero healthy targets if all instances were in the failed AZ.

Answer

Enable cross-zone load balancing on the Application Load Balancer.

Answer

Use an Amazon Route 53 health check to route traffic away from a failed AZ.

Answer

Attach an Elastic IP address to each instance in the Auto Scaling group to ensure IP persistence.

Question 10

A company runs a stateless web application on Amazon EC2 instances in an Auto Scaling group across two Availability Zones. The SysOps administrator needs to ensure that the application can tolerate a failure of an entire Availability Zone. Which configuration is required?

Accepted Answer

Use an Application Load Balancer (ALB) that spans both Availability Zones with health checks enabled.. An Application Load Balancer (ALB) that spans both Availability Zones with health checks enabled distributes incoming traffic across EC2 instances in multiple AZs. If an entire AZ fails, the ALB automatically routes traffic only to healthy instances in the remaining AZ, ensuring the stateless web application remains available. Health checks detect instance or AZ failure and remove unhealthy targets from the load balancer's target group, which is essential for fault tolerance.

Answer

Enable termination protection on all Amazon EC2 instances.

Answer

Place the Amazon EC2 instances in a cluster placement group.

Answer

Associate an Elastic IP address with the primary instance.

Question 11

A company runs a production Amazon RDS for PostgreSQL DB instance in a single Availability Zone (AZ). The SysOps administrator needs to improve database availability so that in the event of a database failure or AZ outage, a standby instance is automatically promoted with minimal downtime. Which configuration should the administrator enable?

Accepted Answer

Enable Multi-AZ deployment on the DB instance.. Multi-AZ deployment automatically creates and maintains a synchronous standby replica in a different Availability Zone. In the event of a failure or AZ outage, Amazon RDS automatically fails over to the standby, typically within 60–120 seconds, with no manual intervention required. This meets the requirement for automatic promotion with minimal downtime.

Answer

Enable automated backups with a retention period of 35 days.

Answer

Create a read replica in another Availability Zone.

Answer

Schedule manual snapshots to be taken every hour and restore from the latest snapshot when needed.

Question 12

A production RDS MySQL database stores financial records. The team needs the ability to restore the database to any point within the last 7 days in case of accidental data deletion. Automated backups are currently disabled. What must be configured?

Accepted Answer

Enable automated backups and set the backup retention period to 7 days. To restore an RDS MySQL database to any point within the last 7 days, you must enable automated backups and set the backup retention period to 7 days. Automated backups enable point-in-time recovery (PITR), which allows restoration to any second within the retention window using binary logs. Without automated backups, RDS cannot perform PITR, even if manual snapshots exist.

Answer

Create a manual DB snapshot every night using the AWS CLI on a schedule

Answer

Enable Multi-AZ to maintain a synchronous standby replica in a second Availability Zone

Answer

Enable RDS read replicas and promote one if data deletion occurs

Question 13

An Auto Scaling group launches new EC2 instances when CPU exceeds 70 percent. The instances take 4 minutes to bootstrap (install software, register with a service discovery system, and warm up caches). Without a hook, the load balancer routes traffic to new instances before they are ready, causing 503 errors. What is the correct solution?

Accepted Answer

Add a lifecycle hook on the autoscaling:EC2_INSTANCE_LAUNCHING transition; signal CompleteLifecycleAction(CONTINUE) when bootstrap finishes. Lifecycle hooks allow the Auto Scaling group to pause instance launch until a custom action (e.g., bootstrap completion) is finished. By adding a hook on the autoscaling:EC2_INSTANCE_LAUNCHING transition, the instance is held in a 'pending:wait' state. Once the bootstrap script calls CompleteLifecycleAction with the CONTINUE result, the instance transitions to 'InService' and can then be registered with the load balancer, preventing premature traffic and 503 errors.

Answer

Increase the load balancer health check grace period to 10 minutes to give instances time to bootstrap

Answer

Increase the warm-up time in the Auto Scaling group's instance refresh configuration

Answer

Use a weighted target group with 0 weight for new instances until they are confirmed healthy

Question 14

Regulatory requirements mandate that all RDS and EBS backups are replicated to a secondary AWS region within 24 hours of creation. The company has workloads in us-east-1 and must replicate backups to eu-west-1. Restoring from the secondary region must be possible without manual copying steps during a disaster. What service and configuration implements this requirement?

Accepted Answer

Create an AWS Backup plan with a cross-Region copy rule that replicates recovery points to a backup vault in eu-west-1 within 24 hours. AWS Backup is the correct service because it natively supports cross-Region copy rules that automatically replicate recovery points (including RDS snapshots and EBS snapshots) to a backup vault in a secondary Region within a specified time window. This meets the 24-hour replication requirement and enables direct restores from the secondary Region without manual copying, as the backup vault in eu-west-1 contains the replicated recovery points ready for use.

Answer

Schedule a Lambda function that calls CreateDBSnapshot and CopyDBSnapshot to replicate RDS snapshots, and CreateSnapshot and CopySnapshot for EBS volumes to eu-west-1

Answer

Enable RDS automated backups with cross-region replication and configure EBS snapshot copy separately using Data Lifecycle Manager

Answer

Use S3 Cross-Region Replication to replicate the backup bucket containing RDS and EBS snapshots to eu-west-1

Question 15

An EC2 instance runs a database on a 2 TB EBS gp3 volume. After a corruption event, the team must restore from a snapshot. When they detach the corrupted volume, attach a new volume restored from the snapshot, and start the database, performance is 10 to 20 times lower than normal for the first two hours. What causes this behavior, and what feature eliminates it?

Accepted Answer

Enable Fast Snapshot Restore (FSR) on the snapshot in the target Availability Zone before creating the replacement volume. When you create an EBS volume from a snapshot, the volume's data blocks are lazily loaded from Amazon S3 on first access. This causes high latency and low IOPS until all blocks are fetched. Fast Snapshot Restore (FSR) pre-initializes the volume in a specific Availability Zone, eliminating the need for lazy loading and providing full performance immediately.

Answer

Use a Provisioned IOPS (io2) volume type instead of gp3 to get higher IOPS during initialization

Answer

Run a full dd or fio pre-warm pass over the volume after attaching it but before starting the database

Answer

Increase the EBS volume size to 4 TB when restoring from the snapshot to get double the throughput baseline