Elastic Compute Cloud
A company has a set of EC2 Instances hosted on the AWS Cloud. These instances form a web server farm which services a web application accessed by users on the Internet. Which of the following would help make this architecture more fault tolerant? Choose 2 answers from the options given below.
A. Ensure the instances are placed in separate Availability Zones.
B. Ensure the instances are placed in separate regions.
C. Use an AWS Load Balancer to distribute the traffic.
D. Use Auto Scaling to distribute the traffic.
A. & C.
AWS Documentation mentions the following: A load balancer distributes incoming application traffic across multiple EC2 Instances in multiple Availability Zones. This increases the fault tolerance of your applications. Elastic Load Balancing detects unhealthy instances and routes traffic only to healthy instances.
For more information on the AWS Classic Load Balancer, please visit the following URL:
https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/introduction.htmlNote:Autoscaling will not create an ELB automatically you need to manually create it in the same region as the AutoScaling group.Once you create an ELB, and attach the load balancer to the autoscaling group, it automatically registers the instances in the group and distributes incoming traffic across the instances.The following steps provides you information on attaching a load balancer to autoscaling group. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.On the navigation pane, under Auto Scaling, choose Auto Scaling Groups.Select your group.On the Details tab, choose Edit.Do one of the following:[Classic Load Balancers] For Load Balancers, select your load balancer.[Target groups] For Target Groups, select your target group.Choose Save.As per AWS,You can automatically increase the size of your Auto Scaling group when demand goes up and decrease it when demand goes down. As the Auto Scaling group adds and removes EC2 instances, you must ensure that the traffic for your application is distributed across all of your EC2 instances. The Elastic Load Balancing service automatically routes incoming web traffic across such a dynamically changing number of EC2 instances. Your load balancer acts as a single point of contact for all incoming traffic to the instances in your Auto Scaling group. To use a load balancer with your Auto Scaling group, create the load balancer and then attach it to the group.For more information:https://docs.aws.amazon.com/autoscaling/ec2/userguide/autoscaling-load-balancer.htmlhttps://docs.aws.amazon.com/autoscaling/ec2/userguide/attach-load-balancer-asg.html
