[anthonyhenry]

QUESTION 59
A Solutions Architect needs to use AWS to implement pilot light disaster recovery for a three-tier web application hosted in an on-premises datacenter.
Which solution allows rapid provision of working, fully-scaled production environment?
A. Continuously replicate the production database server to Amazon RDS.
Use AWS CloudFormation to deploy the application and any additional servers if necessary.
B. Continuously replicate the production database server to Amazon RDS.
Create one application load balancer and register on-premises servers.
Configure ELB Application Load Balancer to automatically deploy Amazon EC2 instances for application and additional servers if the on-premises application is down.
C. Use a scheduled Lambda function to replicate the production database to AWS.
Use Amazon Route 53 health checks to deploy the application automatically to Amazon S3 if production is unhealthy.
D. Use a scheduled Lambda function to replicate the production database to AWS.
Register on-premises servers to an Auto Scaling group and deploy the application and additional servers if production is unavailable.
Correct Answer: B Section: (none)
Explanation

参考答案是B，我的思考路线是这样的，觉得B不对，因为ELB不能注册线下的服务器的。D也不对，Auto Scaling group也不能注册线下服务器，A不对，觉得和CloudFormation没什么关系。 剩下的C可能会是对的

 

[挨踢小茶]

我觉得B是正确答案，因为ALB除了能关联EC2实例之外，还可以关联IP地址的（详情看看https://aws.amazon.com/cn/blogs/aws/new-application-load-balancing-via-ip-address-to-aws-on-premises-resources/）。所以B比较全面。

[Ken]

我倒是觉得选A。ELB无法自动部署EC2。

A倒是可以完成复制生产环境的需求。

https://kenmlai.me/try%20to%20elaborate%20-%20aws/2019/10/17/Q59-SAA/

[挨踢小茶]

我对B的理解是ELB注册on-premise的机器，然后做健康检查，如果机器失效了，会自动从AWS上部署机器（Auto Scaling Group），来做应用的高可用。

[xj3]

记得小茶在另外的帖子里提到了既然有pilot light DR，应该选A的。

另外ELB如果要支持on-prem instance的话是有条件的（我记得要有DX或VPN吧？）这一点题干没有提及。

[叶威]

C肯定是错的，因为route 53 的health checks是没有办法实现自动部署Application的，更不是部署到S3了

[作者]

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