Final answer:
A crossover cable is used to connect two similar devices directly, which allows for proper communication by connecting the transmitting pins on one end to the receiving pins on the other end. Newer NICs might not require a crossover cable due to the Auto-MDI/MDI-X feature.
Step-by-step explanation:
When connecting two computers directly, using a crossover cable is traditionally necessary because it allows for the correct transmitting and receiving pins to be connected to one another. In a crossover cable, the wire that transmits data from computer A is connected to the wire that receives data on computer B, and vice versa. This setup is crucial when the devices being connected are similar, as in this case with two computers.
Modern network interface cards (NICs) can often automatically cross over the connection when needed, a feature known as Auto-MDI/MDI-X. If Erin's computers have this feature, a standard Ethernet cable could be used instead. However, if the computers' NICs do not support Auto-MDI/MDI-X, then Erin definitely should use a crossover cable to connect the two computers directly.