Which term is best associated with the controlled access of external users to a private network?

The term that best describes the controlled access of external users to a private network is "Extranet." An extranet extends certain functionalities of a private network (typically an intranet) to outside users, such as customers, vendors, or partners, enabling secure communication and collaboration while maintaining the privacy and security of the internal network.

By using an extranet, organizations can share specific data and resources with selected external entities in a controlled manner, often through secure login credentials or access permissions. This allows for effective collaboration without compromising sensitive internal information.

In contrast, other terms outlined in the options refer to different networking concepts: an intranet is a private network accessible only within an organization, the internet is the global system of interconnected networks, and a VPN (Virtual Private Network) is a technology that allows secure connections over a public network, but doesn’t inherently describe access for external users to a private network like an extranet does.