A workload domain consists of VMware ESXi hosts managed by a single VMware vCenter Server instance, storage for workload data, and network equipment to connect to the data center.
Workload Domain Characteristics
Workload domains can include different combinations of ESXi hosts and network equipment that can be set up with varying levels of hardware redundancy and varying quality of components. Workload domains must be reachable through a layer 3 network.
A workload domain represents a logical boundary of functionality, managed by a single vCenter Server instance. The workload domain is not defined by any physical properties such as physical location.
For the deployment of any size, consider homogeneity and easy replication. Different workload domains can provide different characteristics for varying requirements. For example, one workload domain can use full hardware redundancy for each component for increased availability. Another workload domain in the same deployment can use low-cost hardware without any hardware redundancy. These variations make the architecture suitable for different workload requirements.