Hi Brannen,

You would use secondary IP addresses on an interface if you are unable to expand a subnet in a location. I've got about 50 wireless AP's, and static hosts (printers/servers) in a location that I just can not resubnet at this time. I would have to touch each host to change their subnet mask.

I used a secondary subnet to move the DHCP scope out to another subnet, which then freed up about 150 usable IP addresses for additional static hosts (printers).