Q20 — AWS SAA-C03 Ch.15

Question 20 of 100 | ← Chapter 15

Q1120. A company has a three-tier web application. An Application Load Balancer (ALB) is in front of Amazon EC2 instances that are in the ALB target group. An Amazon S3 bucket stores documents.The company requires the application to meet a recovery time objective (RTO) of 60 seconds.Which solution will meet this requirement?

• A. Replicate S3 objects to a second AWS Region. Create a second ALB and a minimum set of EC2 instances in the second Region. Ensure that the EC2 instances are shut down until they are needed.Configure Amazon Route 53 to fail over to the second Region by using an IP-based routing policy.
• B. Use AWS Backup to take hourly backups of the EC2 instances. Back up the S3 data to a second AWS Region. Use AWS CloudFormation to deploy the entire infrastructure in the second Region when needed.
• C. Create daily snapshots of the EC2 instances in a second AWS Region. Use the snapshots to recreate the instances in the second Region. Back up the S3 data to the second Region. Perform a failover by modifying the application DNS record when needed.
• D. Replicate S3 objects to a second AWS Region. Create a second ALB and a minimum set of EC2 instances in the second Region.Ensure that the EC2 instances in the second Region are running.Configure Amazon Route 53 to fail over to the secondary Region based on health checks. ✓

Correct Answer: D. Replicate S3 objects to a second AWS Region. Create a second ALB and a minimum set of EC2 instances in the second Region.Ensure that the EC2 instances in the second Region are running.Configure Amazon Route 53 to fail over to the secondary Region based on health checks.

Explanation

To meet the company's Recovery Time Objective (RTO) of 60 seconds for a three-tier web application (ALB + EC2 instances + S3 bucket), the solution must ensure rapid failover to a secondary region with minimal downtime. Let's analyze the options:Key Requirements:RTO 60 seconds: The application must recover within 60 seconds after a failure. Multi-Region Resilience: The solution must replicate data and infrastructure to a secondary AWS Region. Automated or Minimal-Manual Failover: Manual steps (e.g., spinning up instances) would exceed the RTO. Health-Based Failover: Failover should trigger only if the primary region is unhealthy.Option Analysis:Option A:S3 Replication: S3 objects are replicated to a secondary region (good). Secondary ALB & EC2 Instances: Deployed in the secondary region but shut down until needed. Route 53 Failover: Uses an IP-based routing policy (not health-based).Why This Fails:EC2 instances are shut down Starting them takes minutes (violates 60-second RTO). IP-based routing does not verify health (may fail over unnecessarily).Option B:AWS Backup: Takes hourly backups of EC2 instances (too slow for RTO 60s). S3 Cross-Region Backup: S3 data is backed up to a secondary region (good). AWS CloudFormation: Deploys infrastructure in the secondary region when needed (manual/slow).Why This Fails:Hourly backups + manual CloudFormation deployment RTO exceeds 60 seconds.Not suitable for rapid failover.Option C:Daily Snapshots: EC2 snapshots are taken daily (too slow for RTO 60s). S3 Cross-Region Backup: S3 data is backed up to a secondary region (good). Manual Failover: Requires modifying DNS records (manual/slow).Why This Fails:Daily snapshots + manual DNS update RTO exceeds 60 seconds.Not suitable for rapid failover.Option D:S3 Replication: S3 objects are replicated to a secondary region (good). Secondary ALB & Running EC2 Instances: Deployed in the secondary region and always running (ready for failover).Route 53 Failover: Uses health checks to trigger failover (only if primary is unhealthy).Why This Works:EC2 instances are always running No startup delay (meets 60-second RTO).Health-based failover ensures failover only when needed.S3 replication ensures data availability in the secondary region.Best Choice: Option DAlways-Running Secondary Instances: Ensures rapid failover (no startup delay). Health-Based Route 53 Failover: Automatically switches traffic if the primary region fails. S3 Replication: Ensures data is available in the secondary region.Meets RTO 60 seconds.Final Answer:D. Replicate S3 objects to a second AWS Region. Create a second ALB and a minimum set of EC2 instances in the second Region. Ensure that the EC2 instances in the second Region are running. Configure Amazon Route 53 to fail over to the secondary Region based on health checks.