How do you network three computers without a hub?

One Answer:

It is possible to connect two computers without using a hub by using a switch instead. A switch is better than a hub because it creates a collision domain (CD) and stops them from happening when two devices try and send frames at the same time. Rather than buying a cross-over cable to connect two computers together, you can use two straight-through cables (your average, everyday network cable) and connect them to a switch. This also allows for growth where you can add more computers to the switch if the network grows.

Another Answer:

With Ethernet, you can use a crossover cable to connect two computers without using a hub, switch, or existing network. Crossover cables are Ethernet cables that have the send and receive wires (pins) switched along the length of the cable. The pins that send information from one computer are connected to the pins that receive information for the second computer. You can use a regular cable if they are modern computers.