You have started a new job and are reviewing your company’s infrastructure on AWS You notice
one web application where they have an Elastic Load Balancer (&B) in front of web instances in an
Auto Scaling Group When you check the metrics for the ELB in CloudWatch you see four healthy
instances In Availability Zone (AZ) A and zero in AZ B There are zero unhealthy instances.
What do you need to fix to balance the instances across AZs?
A.
Set the ELB to only be attached to another AZ
B.
Make sure Auto Scaling is configured to launch in both AZs
C.
Make sure your AMI is available in both AZs
D.
Make sure the maximum size of the Auto Scaling Group is greater than 4
B is Right
B
b
b
Ans:B
Answer is : B
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When one Availability Zone becomes unhealthy or unavailable, Auto Scaling launches new instances in an unaffected Availability Zone. When the unhealthy Availability Zone returns to a healthy state, Auto Scaling automatically redistributes the application instances evenly across all of the Availability Zones for your Auto Scaling group. Auto Scaling does this by attempting to launch new instances in the Availability Zone with the fewest instances. If the attempt fails, however, Auto Scaling attempts to launch in other Availability Zones until it succeeds.
Link : http://docs.aws.amazon.com/autoscaling/latest/userguide/as-add-availability-zone.html