With reference to computer networking, which of the following statements is…

Concept — An intranet is a private network that belongs to a single organization. Two properties define it together: its boundary, meaning only that organization's authorized members can reach it, and its technology base, meaning it is built on the very same TCP/IP protocol suite and web technologies (HTTP, HTML, DNS, e-mail) that the public Internet runs on. Keeping outsiders out is an administrative and security decision enforced by firewalls and authentication; it is not achieved by inventing different protocols.

Application — A statement that places the network within an organization and says it uses Internet protocols and technologies names both defining properties at once: the organizational boundary and the reuse of Internet standards. That is exactly the definition of an intranet, so it is the true statement here.

Cross-check — Each of the remaining statements is the standard definition of a different idea:

• A network that covers a wide area with rented telecommunication lines is a WAN. A WAN is classified by geographic scale and by leased carrier links, not by who owns or may use it; an intranet can itself run over a WAN.

• A single computer connected to the Internet acting as a gateway for other devices is Internet connection sharing, that is, a gateway or proxy host. It is a connectivity arrangement for one machine, not a category of network.

• A widely available public network of interconnected computer networks is the definition of the Internet itself. Its defining trait is universal public reachability, which is the opposite of the restricted access that makes a network an intranet.

Result — Organizational scope plus Internet technology is what defines an intranet, so the statement describing a network within an organization that uses Internet protocols and technologies is the true one.