SAA-C03 Question 193
Select 3A company runs a mission-critical web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application is deployed across two Availability Zones (AZs) in the US-East-1 Region. The company wants to implement a failover strategy so that traffic is directed to a backup Region (US-West-2) in case the entire US-East-1 Region becomes unavailable. How can they achieve this failover scenario?
- A
Use Route 53 with a failover routing policy to direct traffic to the backup Region when the primary Region is unhealthy.
- B
Configure an Auto Scaling group in the backup Region to automatically spin up EC2 instances when traffic is routed there.
- C
Enable Cross-Region Replication (CRR) for the web application's Amazon S3 buckets to ensure data availability in the backup Region.
- D
Use an Elastic Load Balancer (ELB) with health checks to automatically redirect traffic between Regions.
- E
Deploy the application in the backup Region and keep it running in an active-active configuration.
Show answer and explanation
Correct answers: A, B, C
Explanation
To implement a failover strategy, Route 53 with failover routing ensures traffic is redirected to the backup Region when the primary Region becomes unavailable. An Auto Scaling group in the backup Region automatically provisions necessary resources during failover. Cross-Region Replication (CRR) for S3 ensures that application data is consistent and available in the backup Region. ELBs cannot redirect traffic between Regions, and an active-active configuration does not align with the active-passive failover requirement specified in the scenario.
- A. Correct.
This is correct. Route 53 with a failover routing policy can monitor the health of resources and direct traffic to a backup Region if the primary Region becomes unavailable.
- B. Correct.
This is correct. An Auto Scaling group in the backup Region ensures that application resources are automatically provisioned when traffic is redirected there due to a failover.
- C. Correct.
This is correct. Enabling Cross-Region Replication (CRR) for S3 ensures that application data is available in the backup Region, which is critical for seamless failover.
- D. Incorrect.
This is incorrect. Elastic Load Balancers (ELBs) do not support automatic redirection of traffic between Regions, as they operate within a single Region.
- E. Incorrect.
This is incorrect. While an active-active configuration is a valid approach, the scenario specifically asks for a failover strategy, which implies active-passive setup rather than both Regions actively serving traffic simultaneously.