To put it as simply as possible, in any given network range the very first address and the very last address are not usable for hosts. The first address is the network address, and the last address is the broadcast address.
So for 192.168.1.0/24 you'd have:
192.168.1.0 - Network address (NOT usable for hosts)
192.168.1.1 through 192.168.1.254 - Free IPs (Usable for hosts)
192.168.1.255 - Broadcast address (NOT usable for hosts)
And for /25 sub-nets (and all others besides) it'd be the same: the first address in the range and the last address in the range are not usable for hosts.
Thank you Drysdalk . i believe i didn't understood properly what a single ip address means. From your above explanation . for e.g.
Does all those ip are list of single ip address. i believe list of hosts in ip class means list of single ip address. Does my public ip address as mentioned
means one of hosts from class A public ip address .
Firstly, from just looking at a single IP, you can't tell how large the network it's a part of is. You need to know the netmask. So for example, if I had an IP of 192.168.1.10, that doesn't tell you anything at all about how large or small the network I'm a part of is.
But if I tell you the netmask - e.g. 192.168.1.10/24 or 192.168.1.10/255.255.255.0 - then you know it's part of a network of 256 addresses, running from 192.168.1.0 to 192.168.1.255.
If on the other hand I'd told you the netmask was 192.168.1.10/25 or 192.168.1.10/255.255.255.128 - then you'd know it was part of a network of 128 addresses going from 192.168.1.0 to 192.168.1.127.
And again, in every network, the very first address and the very last address are not usable for hosts, as they are reserved for other purposes.
You can also get plenty of other netmasks than the old simple Class A, B, C notation tells you. For instance I could just have easily told you my netmask was 192.168.1.10/28, in which case you'd then be able to calculate that the network I was a part of runs from 192.168.1.0 to 192.168.1.15, and conists of 16 IP addresses.
So just from looking at an IP you can't tell anything about the size of the network. And these days, there are far more netmasks and subnet sizes that are far more common than the old Class A/B/C notation.
As seen on Digg.com, here is my ip addressing article in full...
Original Subnetting in 11 Steps article
Subnetting in 11 Steps
There are a few things that you will need to know first. I personally use 11 rules that I learned from Mike Vana. Below you will find the 11 rules as well as... (1 Reply)
We have subnetted our Internal Network. We used an I.P. range of 172.16.16.0-254, 172.16.17.0-254, 172.16.18.0-254, 172.16.19.0-254 and mask 255.255.252.0. We created a subnet range of 172.16.10.0-254 and maske 255.255.255.0. Our routers are configure to route to approprate network. We are able... (2 Replies)