The user has created an Elastic Load Balancer with the availability zone and wants to add more zones to the existing ELB. The user can do so in two ways: From the console or CLI, add new zones to ELB; Launch instances in a separate AZ and add instances to the existing ELB. Reference: http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/enable- disable-az.html