Hi Eric,
I think @iank99 has covered everything here. To add a couple of further comments:
There are many different approaches to running network cabling above 100m, most of which come down to personal preference and the specific requirements of each system.
If you need a cable run of more than 200m, I would be tempted to go with Ian's suggestion, and move over to fibre for the cable run...
As Ian suggests, if you need a cable run between 100m and 200m, you could get away with putting a small Ethernet switch mid way along the line. Depending on the system you are creating, it could be useful to add a wireless access point at this location too. I would not recommend "daisy-chaining" multiple switches to achieve this, as the more "hops" you add, the more latency there will eventually be.
The setup Ian is talking about here is specialist equipment. Personally, I wouldn't consider Wi-Fi for this, but YMMV. If you need to get a DMX universe remotely, then sending DMX wirelessly will be less of a headache than wirelessly sending your Ethernet network a great distance.
If you have any questions, let us know.
Edward