Which architecture should the solutions architect choose that provides high availability?
Create an Auto Scaling group that uses three instances across each of two Regions.
Modify the Auto Scaling group to use three instances across each of two Availability Zones.
Create an Auto Scaling template that can be used to quickly create more instances in another Region.
Change the ALB in front of the Amazon EC2 instances in a round-robin configuration to balance traffic to the web tier.
Explanations:
Running instances across two Regions does not provide high availability for the application within a single Region’s Availability Zones, which can lead to increased latency and complexity.
Modifying the Auto Scaling group to use instances across two Availability Zones ensures redundancy and high availability within the same Region, as it can withstand the failure of one Availability Zone.
Creating an Auto Scaling template for instances in another Region does not provide high availability for the existing application setup in its current Region. High availability requires instance distribution within the same Region.
Changing the ALB to round-robin configuration does not enhance high availability; it only changes traffic distribution. The underlying instances still need to be spread across multiple Availability Zones for true high availability.
I suspect that the answer is:
Modify the Auto Scaling group to use three instances across each of two Availability Zones.