AustinMorris:
Wikipedia tells me that cat5 can't go longer than 100m.
That is for Ethernet. Other protocols like RS485 can go many kilometers on Cat5 cable.
The length limit for Ethernet is based on the speed and duration of the packets so a minimum-size packet is actually 100m long as it travels down the wire. The limit is necessary for collision detection, so a transmitter can detect another transmitter stepped on its transmission.