Auto-Scaling Quiz
You have a business-critical two-tier web application currently deployed in 2 Availability Zones in a single region, using Elastic Load Balancing and Auto Scaling. The app depends on synchronous replication at the database layer. The application needs to remain fully available even if one application AZ goes offline and if Auto Scaling cannot launch new instances in the remaining AZ. How can the current architecture be enhanced to ensure this?
A. Deploy in 2 regions using Weighted Round Robin with Auto Scaling minimums set at 50%peak load per region.
B. Deploy in 3 AZ with Auto Scaling minimum set to handle 33 per cent peak load per zone.
C. Deploy in 3 AZ with Auto Scaling minimum set to handle 50 per cent peak load per zone.
D. Deploy in 2 regions using Weighted Round Robin with Auto Scaling minimums set at 100%peak load per region.
C. Deploy in 3 AZ with Auto Scaling minimum set to handle 50 per cent peak load per zone.
Since the requirement states that the application should never go down even if an AZ is not available, we need to maintain 100% availability.
Options A and D are incorrect because region deployment is not possible for ELB. ELBs can manage traffic within a region and not between regions. Option B is incorrect because even if one AZ goes down, we would be operating at only 66% and not the required 100%.
For more information on Auto Scaling, please visit the below URL:
https://aws.amazon.com/autoscaling/
