GSLB service is the representation of a global application deployed at multiple sites. The GSLB service configuration defines the FQDN of the application, the backing virtual services in various sites, and the priority or ratios governing the selection of a particular virtual service at any given time. The configuration also defines the health-monitoring methods by which unhealthy components can be identified so that the best alternatives may be selected.
The following are the two categories of GSLB service health monitoring:
Control-plane
Data-plane
You can apply one or both on a per-application basis.
The health monitor is applicable for GSLB only if the is_federated option is checked in the health monitor configuration.
For more details on GSLB, refer to the GSLB guide.