The “Enclosed Network” phase exists because systems or groups sometimes need a secure, controlled environment before opening access to everyone. It helps protect data, test stability, and make sure everything works correctly without outside interference.

Think of it like a beta version of a game — developers let a small group in first to find bugs, improve performance, and prevent security problems before the full public launch. It also helps organizations control traffic, manage risks, and keep sensitive information private until the network is ready for wider use.