While I understand the link, I find this statement odd:
"An example: If your DHCP pool is from 192.168.0.10 to 192.168.0.250, and you define a static mapping for 192.168.0.25. If the PC that normally has 192.168.0.25 is ever offline, another device could be assigned 192.168.0.25. When the other machine powers back up, it will not be able to get 192.168.0.25 because it is currently in use."
What's the point of using MAC addresses if the reserved addresses can be assigned to other machine? Surely that's the point of using the MAC address. All other dhcp servers I've used allow the assignment of addresses from the range. This was why I was confused.