AWS SAA-C02真题2

2. A company has a multi-tier application that runs six front-end web servers in an Amazon EC2 Auto Scaling group in a single AZ behind an ALB. A solution architect needs to modify the infrastructure to be highly available without modifying the application.

Which architecture should the solutions architect choose that provides high availability?

A. Create an Auto Scaling group that uses three instances across each of two Regions.

B. Modify the Auto Scaling group to use three instances across each of two AZs

C. Create an Auto Scaling template that can be used to quickly create more instances in another Region.

D. Change the ALB in front of the Amazon EC2 instances in a round-robin configuration to balance traffic to the web tier.

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高可用方案选择multi AZs + Auto Scaling, 通过修改现有ASG以适应多个AZ可以非常简单地做到高可用。ASG将自动平衡负载，不需要手动为每个AZ指定instance。请参考https://aws.amazon.com/ec2/autoscaling/       Answer: B

Amazon EC2 Auto Scaling will perform three main functions to automate fleet management for EC2 instances:

• Monitor the health of running instances

Amazon EC2 Auto Scaling ensures that your application is able to receive traffic and that EC2 instances are working properly. Amazon EC2 Auto Scaling periodically performs health checks to identify any instances that are unhealthy.

• Replace impaired instances automatically

When an impaired instance fails a health check, Amazon EC2 Auto Scaling automatically terminates it and replaces it with a new one. That means that you don’t need to respond manually when an instance needs replacing.

• Balance capacity across Availability Zones

Amazon EC2 Auto Scaling can automatically balance instances across zones, and always launches new instances so that they are balanced between zones as evenly as possible across your entire fleet.