ManageEngine DDI Central has two components DDI Console and DDI Node Agent to be downloaded.
DDI Console provides centralized User Interface to manage all your DNS, DHCP clusters and also helps to manage your IP address inventory.
DDI Node Agent must be deployed on all your DNS and DHCP servers to ensure continuous visibility of your DNS and DHCP clusters. It is a small light-weight agent which communicates with the DDI Console and helps to discover the existing configuration and provision new configuration changes from the DDI Console.