anything ending in .255 is a broadcast address, anything ending in .0 is network number (or net ID). Both are automatically in use (reserved) and can't be used as host ip.
Private ranges are :
10.0.0.0-10.255.255.255
172.16.0.0-172.31.255.255
192.168.0.0-192.168.255.255
There also something called APIPA, short for "Automatic Private IP Addressing". This ranges from 169.254.0.1 through 169.254.255.254 and is assigned in Windows when a host asks a DHPC server for a dynamic address and the DHPC server does not respond.
I hope this answers your questions
