Elastic Compute Cloud
You have an application running in us-west-2 requiring 6 EC2 Instances running at all times. With 3 Availability Zones in the region viz. us-west-2a, us-west-2b, and us-west-2c, which of the following deployments provides fault tolerance if an Availability Zone in us-west-2 becomes unavailable?
Choose 2 answers from the options given below.
A. 2EC2 Instances in us-west-2a, 2 EC2 Instances in us-west-2b, and 2 EC2 Instances in us-west-2c
B. 3 EC2 Instances in us-west-2a, 3 EC2 Instances in us-west-2b, and 3 EC2 Instances in us-west-2c
C. 4 EC2 Instances in us-west-2a, 2 EC2 Instances in us-west-2b, and 2 EC2 Instances in us-west-2c
D. 6 EC2 Instances in us-west-2a, 6 EC2 Instances in us-west-2b, and no EC2 Instances in us-west-2c
B. & D.
Option A is incorrect because, even if one AZ becomes unavailable, you would only have 4 instances available. This does not meet the specified requirements.
Option B is incorrect because, in the case of either us-west-2a or us-west-2b becoming unavailable, you would only have 3 instances available. Even this does not meet the specified requirements.
Option C is incorrect because, if us-west-2a becomes unavailable, you would only have 4 instances available. This also does not meet the requirements.
For more information on AWS Regions and Availability Zones, please visit the following URL:
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.RegionsAndAvailabilityZones.html
