RODC is use for delegation usually like you have administrator in the sites you don’t want them to have more access on AD just to monitor and maintain it you can install RODC . Simply for security
its is quite understand able by its name read only domain controller
RODC as the name suggests, is a read only domain controller. With the help of delegation, you can delegate the task of managing RODC to the normal user without granting him the rights of any administrator. This helps in preventing your DC’s from any unauthorise use.
RODC helps you minimise the administration on the Read only domain controller.