SOA-C02 Reliability and Business Continuity Practice Test 4 — 15 Questions

Question 1

A web application runs on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer. To achieve high availability, what is the minimum number of Availability Zones (AZs) that must be configured for the Auto Scaling group?

Accepted Answer

2. For high availability, an Auto Scaling group must span at least two Availability Zones (AZs) to ensure that if one AZ fails, the application remains available from the other AZ. A single AZ would create a single point of failure, violating the high-availability requirement. The Application Load Balancer distributes traffic across healthy instances in all configured AZs, so two AZs are the minimum to achieve fault tolerance.

Answer

1

Answer

3

Answer

4

Question 2

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 3

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. Option A is correct because 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 4

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 5

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

Question 6

Drag and drop the steps to set up an AWS Site-to-Site VPN connection into the correct order.

Question 7

Drag and drop the steps to set up an Amazon S3 bucket policy to grant cross-account access into the correct order.

Question 8

Match each AWS storage service to its description.

Question 9

Match each AWS backup and disaster recovery service to its feature.

Question 10

A company is running a critical web application on EC2 instances behind an Application Load Balancer. The instances are in an Auto Scaling group across two Availability Zones. The company needs to ensure that if an entire Availability Zone fails, the application remains available. Which configuration meets this requirement?

Accepted Answer

Configure the Auto Scaling group to launch instances in at least two Availability Zones.. Spreading instances across multiple Availability Zones ensures that if one AZ fails, the other AZ continues to serve traffic. Option B is correct because it explicitly uses multiple AZs. Option A is wrong because using a single AZ does not provide AZ-level fault tolerance. Option C is wrong because Amazon CloudFront is a CDN, not a solution for AZ failure. Option D is wrong because increasing instance size does not provide AZ redundancy.

Answer

Use larger EC2 instance types to handle the load during a failure.

Answer

Use Amazon CloudFront to distribute traffic across multiple regions.

Answer

Launch all instances in the same Availability Zone to reduce latency.

Question 11

A company uses a Multi-AZ RDS for MySQL instance for its production database. During a maintenance window, the primary instance fails and a failover occurs. However, the application experiences a 5-minute downtime. The application uses a DNS CNAME record pointing to the RDS endpoint. What is the MOST likely cause of the downtime?

Accepted Answer

The application was using a cached DNS resolution for the RDS endpoint.. Option B is correct because DNS caching at the client or resolver level can cause the application to continue using the old IP address until the TTL expires. Option A is wrong because Multi-AZ failover typically completes within minutes. Option C is wrong because RDS endpoints automatically update. Option D is wrong because Multi-AZ failover is automatic.

Answer

The application was not configured to retry connections after a failover.

Answer

The RDS endpoint changed after failover and the application did not update.

Answer

The failover process took longer than expected due to a large transaction log.

Question 12

A company wants to back up its on-premises file server to AWS. The backup must be encrypted in transit and at rest. Which AWS service should the company use to meet these requirements?

Accepted Answer

AWS Storage Gateway (File Gateway) backed by Amazon S3.. Option B is correct because AWS Storage Gateway's File Gateway can back up on-premises files to S3 with encryption in transit (using TLS) and at rest (using S3 server-side encryption). Option A is wrong because S3 alone does not provide a backup agent for on-premises. Option C is wrong because EBS volumes are for EC2, not on-premises. Option D is wrong because CloudFormation is for infrastructure as code.

Answer

Amazon EBS volumes attached to an EC2 instance acting as a file server.

Answer

AWS CloudFormation to replicate the file server configuration.

Answer

Amazon S3 with server-side encryption and a custom script to upload files.

Question 13

A company has an AWS Lambda function that processes S3 events. The function is critical and must be available even if one Availability Zone fails. How can a SysOps administrator ensure high availability for the Lambda function?

Accepted Answer

No action is required; Lambda functions are inherently highly available within a region.. Option D is correct because AWS Lambda automatically runs across multiple Availability Zones in a region; no additional configuration is needed. Option A is wrong because Lambda is inherently multi-AZ. Option B is wrong because Lambda functions are not tied to AZs. Option C is wrong because the Lambda service itself handles availability.

Answer

Use an Application Load Balancer to distribute events to multiple Lambda functions.

Answer

Configure the Lambda function to run in two subnets in different Availability Zones.

Answer

Deploy the Lambda function in two separate regions and use Route 53 failover.

Question 14

A company runs a stateful web application on EC2 instances in an Auto Scaling group. The application uses a sticky session (session affinity) feature of the Application Load Balancer. During a scale-in event, some users lose their session data. What should the SysOps administrator do to prevent session data loss?

Accepted Answer

Store session state in an external data store such as Amazon ElastiCache.. Option C is correct because storing session data externally (e.g., ElastiCache or DynamoDB) decouples it from the instance, so scale-in does not affect sessions. Option A is wrong because increasing cooldown delays scale-in but does not prevent data loss. Option B is wrong because disabling sticky sessions breaks the application's requirement. Option D is wrong because terminating instances with pending sessions still loses data; the problem is the data is on the instance.

Answer

Disable sticky sessions and use a round-robin routing algorithm.

Answer

Use a lifecycle hook to back up session data before termination.

Answer

Increase the Auto Scaling group's cooldown period to delay termination.

Question 15

A company wants to create a disaster recovery (DR) strategy for its RDS for PostgreSQL database. The primary database is in us-east-1. The company needs a recovery point objective (RPO) of less than 5 minutes and a recovery time objective (RTO) of less than 1 hour. Which solution meets these requirements?

Accepted Answer

Create a cross-region Read Replica in us-west-2 and promote it during a disaster.. Option B is correct because a cross-region Read Replica can be promoted to a primary in another region, achieving low RPO (seconds) and low RTO (minutes). Option A is wrong because snapshots have higher RPO and RTO. Option C is wrong because DMS is for migration, not DR. Option D is wrong because single-region Multi-AZ does not protect against region failure.

Answer

Enable Multi-AZ in us-east-1 and create a standby in a different Availability Zone.

Answer

Use AWS Database Migration Service (DMS) to continuously replicate to an EC2 instance.

Answer

Take daily automated snapshots and copy them to us-west-2.