Which combination of steps will meet these requirements?
(Choose three.)
Use an Elastic Load Balancer to distribute traffic across multiple EC2 instances. Ensure that the EC2 instances are part of an Auto Scaling group that has a minimum capacity of two instances.
Use an Elastic Load Balancer to distribute traffic across multiple EC2 instances. Ensure that the EC2 instances are configured in unlimited mode.
Modify the DB instance to create a read replica in the same Availability Zone. Promote the read replica to be the primary DB instance in failure scenarios.
Modify the DB instance to create a Multi-AZ deployment that extends across two Availability Zones.
Create a replication group for the ElastiCache for Redis cluster. Configure the cluster to use an Auto Scaling group that has a minimum capacity of two instances.
Create a replication group for the ElastiCache for Redis cluster. Enable Multi-AZ on the cluster.
Explanations:
Using an Elastic Load Balancer (ELB) distributes traffic among multiple EC2 instances, improving availability and fault tolerance. An Auto Scaling group with a minimum of two instances ensures that if one instance fails, another can take its place, minimizing downtime.
While using an Elastic Load Balancer is correct, configuring EC2 instances in unlimited mode does not inherently provide fault tolerance or high availability. Unlimited mode allows EC2 instances to use more CPU credits but does not affect their recovery or scaling capabilities.
Creating a read replica in the same Availability Zone does not provide high availability. In case of a failure of the primary instance, promoting a read replica in the same zone may not offer a reliable failover solution, as the same zone can experience outages.
A Multi-AZ deployment for the RDS DB instance provides high availability by automatically replicating data to a standby instance in another Availability Zone. This ensures that if the primary instance fails, the standby can take over, resulting in minimal downtime.
Creating a replication group for ElastiCache improves data availability, but configuring it with Auto Scaling is not standard practice. ElastiCache typically requires a cluster mode for better availability and should use read replicas instead for redundancy.
Creating a replication group for ElastiCache and enabling Multi-AZ allows for higher availability and automatic failover. This configuration ensures that if one node fails, traffic can be redirected to the other node in a different Availability Zone, reducing downtime.
As I see it, the answer is:
Use an Elastic Load Balancer to distribute traffic across multiple EC2 instances. Ensure that the EC2 instances are part of an Auto Scaling group that has a minimum capacity of two instances.