Classic Load Balancers should utilize cross-zone load balancing
Description
This check ensures cross-zone load balancing is activated for Classic Load Balancers. When cross-zone load balancing is turned off, each load balancer node directs traffic solely to the registered targets within its own Availability Zone. Consequently, if the number of registered targets varies among Availability Zones, traffic distribution becomes uneven, potentially leading to overutilization of instances in one zone compared to another. With cross-zone load balancing enabled, each node within the Classic Load Balancer evenly distributes requests across all registered instances in the enabled Availability Zones. For more information, refer to the Cross-Zone Load Balancing section in the Elastic Load Balancing User Guide.
For instructions on enabling cross-zone load balancing in a Classic Load Balancer, refer to the section on enabling cross-zone load balancing in the Classic Load Balancers User Guide.
