text: subnetting question? if an ip address is 198.23.100.0 an i wanted to get 5 subnets out of it, how many binary bits must be borrowed from the host to produce the subnet? 198.23.100.0 first of all its not an ip address, it a network id. an ip address can't have 0 or 255 as the last digit. if its 0 then its network id and if its 255 then it broadcast ip. now "198" i.e class c. hence first three octets for network and 1 octet for host. 5 subnets....borrow 3 bits from host portion. so that 2*3 = 8.  i.e you will get 8 subnets out of which 6 are useful and since you require 5 so this will work. clear up your concepts.  regards