Which solution will make the application highly available?
Provision a subnet in each Availability Zone. Configure the Auto Scaling group to distribute the EC2 instances across both Availability Zones. Configure the DB instance with connections to each network.
Provision two subnets that extend across both Availability Zones. Configure the Auto Scaling group to distribute the EC2 instances across both Availability Zones. Configure the DB instance with connections to each network.
Provision a subnet in each Availability Zone. Configure the Auto Scaling group to distribute the EC2 instances across both Availability Zones. Configure the DB instance for Multi-AZ deployment.
Provision a subnet that extends across both Availability Zones. Configure the Auto Scaling group to distribute the EC2 instances across both Availability Zones. Configure the DB instance for Multi-AZ deployment.
Explanations:
Provisioning a subnet in each Availability Zone is correct, but the DB instance should be configured for Multi-AZ deployment for high availability, not just connected to both networks.
The subnets should be in separate Availability Zones, but extending a subnet across two AZs is not possible. The DB instance should be Multi-AZ for high availability.
Provisioning subnets in separate AZs for the EC2 instances and configuring the DB instance for Multi-AZ deployment ensures high availability for both EC2 and RDS.
While the Auto Scaling group is distributed across two AZs and the DB instance is configured for Multi-AZ, a subnet should not span multiple Availability Zones.
I sort that the answer is:
Provision a subnet in each Availability Zone. Configure the Auto Scaling group to distribute the EC2 instances across both Availability Zones. Configure the DB instance for Multi-AZ deployment.