That is a hard question to answer.
It depends on your needs and setup.
If your server has a UPS, then you should have your switches or hubs and router on a UPS.
Which covers your local network.
Sometimes that can be done with one unit.
Then the clients.
Meaning the pc at say the receptionist desk..
If it is a laptop it already has a battery.
If not then the network is still up but the pc loses connection.
Then it would need a UPS for each PC.
The ideal situation although expensive would be a distributed UPS system that covers remote specific outlets where needed.
