Which network is considered the earliest version of the Internet?

ARPANET is considered the earliest version of the Internet because it was the first network to implement the packet-switching technology that is the foundation of Internet communication today. Established in the late 1960s by the U.S. Department of Defense, ARPANET allowed multiple computers to connect and communicate over long distances, paving the way for the development of various network protocols and eventually leading to the modern Internet.

It was designed primarily to facilitate communication and information sharing among research institutions and military locations. The successful implementation of this network demonstrated the viability of sharing resources across computers, which subsequently influenced the design of future networking protocols and systems.

The other options represent components or organizations related to the Internet or networks but do not fit the definition of an early version of the Internet. For example, DNS (Domain Name System) is a hierarchical system for naming resources on the Internet, while ICANN (Internet Corporation for Assigned Names and Numbers) is responsible for coordinating these naming systems. The Internet of Things (IoT) refers to a network of connected devices that communicate over the Internet and is a recent advancement rather than an early version of it.