3.What is the role of VMware vCenter server?

• vCenter provides a centralized management platform and framework for all ESXi hosts and their respective VMs. vCenter  server allows IT administrators to deploy, manage, monitor, automate, and secure a virtual infrastructure in a centralized fashion. To help provide scalability , vCenter Server leverages a back-end database (Microsoft SQL Server and Oracle are both supported, among others) that stores all the data about the hosts and VMs.