Which university hosted the first ARPANET node?

The first ARPANET node was hosted at UCLA, the University of California, Los Angeles.

UCLA’s Network Measurement Center, led by computer scientist Leonard Kleinrock, received the first Interface Message Processor, or IMP. The IMP acted as an early network router and connected UCLA’s SDS Sigma 7 computer to the emerging ARPANET. UCLA was selected partly because Kleinrock’s team had expertise in measuring and analyzing computer networks.

On October 29, 1969, UCLA programmer Charley Kline attempted to send the word “login” to the Stanford Research Institute. The system crashed after transmitting only the first two letters, “lo.” After engineers adjusted the system, the full login succeeded. This event is commonly remembered as the first ARPANET host-to-host connection.

The first four ARPANET sites were UCLA, SRI, the University of California, Santa Barbara, and the University of Utah. MIT and Carnegie Mellon joined the network later, while Stanford is a common mix-up because SRI received the first message from UCLA and became the second connected site.