Which solution will meet these requirements with the LEAST downtime?
Create an Auto Scaling group and an ELB in the DR Region. Configure the DynamoDB table as a global table. Configure DNS failover to point to the new DR Region’s ELB.
Create an AWS CloudFormation template to create EC2 instances, ELBs, and DynamoDB tables to be launched when necessary. Configure DNS failover to point to the new DR Region’s ELB.
Create an AWS CloudFormation template to create EC2 instances and an ELB to be launched when necessary. Configure the DynamoDB table as a global table. Configure DNS failover to point to the new DR Region’s ELB.
Create an Auto Scaling group and an ELB in the DR Region. Configure the DynamoDB table as a global table. Create an Amazon CloudWatch alarm with an evaluation period of 10 minutes to invoke an AWS Lambda function that updates Amazon Route 53 to point to the DR Region’s ELB.
Explanations:
This solution meets the DR requirements with minimal downtime. The DR region’s Auto Scaling group and ELB are pre-configured, allowing for quick traffic failover. The global DynamoDB table ensures data availability across regions.
This option requires launching resources in the DR region only when necessary, which could result in higher downtime. Additionally, separate DynamoDB tables would not automatically synchronize data.
Although this option uses a global DynamoDB table, the EC2 instances and ELB are created only when needed, causing more downtime during failover as the infrastructure has to be provisioned on demand.
This option may result in unnecessary delays in failover due to the 10-minute CloudWatch alarm period. Additionally, configuring DNS failover with Route 53 is simpler without involving a Lambda function.
I think the answer is:
Create an Auto Scaling group and an ELB in the DR Region. Configure the DynamoDB table as a global table. Configure DNS failover to point to the new DR Region’s ELB.