Hi ,
For Nested Setup please find the below setup
Nested Setup on Same Network
Install ESXi on Your Dell Server
Configure Management Network with 2 Nics - ( Active - Active)
Deploy vCenter on the ESXi
Create New 3 VM with 2 CPU and 2 Core and 12 GB each and Install ESXi on that
For 4 Network Adapter on Each ESXi VM (you can use that for Management , vMotion ,iSCSI etc)
Add all ESXI to vCenter
Nested Setup on Independent Network
Install ESXi on Your Dell Server
Configure Management Network with 2 Nics - ( Active - Active)
Deploy vCenter and Later Move to independent Network
Create VM network without up link and map all VMs over there
Create Windows Server - AD and DNS ( and Two Nics one for Independent Network another Public to access through RDP )
Create New 3 VM with 2 CPU and 2 Core and 12 GB each and Install ESXi on that
For 4 Network Adapter on Each ESXi VM (you can use that for Management , vMotion ,iSCSI etc)
Add all ESXI to vCenter