Which of the following can be used to increase the fault tolerance of an application?

Answer options:

A.Deploying resources across multiple edge locations
B.Deploying resources across multiple VPC’s
C.Deploying resources across multiple Availability Zones
D.Deploying resources across multiple AWS Accounts

Answer – C
Each AZ is a set of one or more data centers. By deploying your AWS resources to multiple Availability zones, you are designing with failure in mind. So if one AZ were to go down, the other AZ’s would still be up and running. Hence your application would be more fault-tolerant.
For more information on AWS Regions and AZ’s, please refer to the below URL:
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.RegionsAndAvailabilityZones.html