What is an ARPANAT?

Answer 1

"The Advanced Research Projects Agency Network (ARPANET), was the world's first operational packet switching network and the core network of a set that came to compose the global internet. The network was funded by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense for use by its projects at universities and research laboratories in the US. The packet switching of the ARPANET was based on designs by Lawrence Roberts of the Lincoln Laboratory."

.wikipedia.org/wiki/ARPANET