Question : Using the .0 IP Address in Supernetted Network

A client network is using the internal IP range of 192.168.0.0 through 192.168.7.255 by supernetting with subnet mask of 255.255.248.0. Since the supernetting causes the 192.168.1.0. 2.0, 3.0, 4.0, 5.0, 6.0 and 7.0 addresses to not be broadcast addresses, they can be used as the IP addresses for network devices (although not preferred).

Here is what I want to know: If somebody introduces a network device with an IP address within the normal range of the network, let's say 192.168.2.1, but gives it a 255.255.255.0 subnet mask, that device will expect the 192.168.2.0 address to be the broadcast address for that subnet, even though it (the 2.0 address) is being used as the IP for another network device. How does this affect the network? Will only the misconfigured device have problems communicating on the network or could this cause issues on the rest of the network as well?

Answer : Using the .0 IP Address in Supernetted Network

I will tell you that from personal experience, you need to exclude all addresses that would typically be broadcase addressese if this is a Windows network. That means 1.255, 2.255, etc. Device that receive these address will not work properly. Below is a link to an article about things to watch for when supernetting a Windows network.

http://support.microsoft.com/kb/281579