While there are certainly newer on-line tools (web pages) that do the same thing, there is nothing like having such a tool available when trying to fix a broken system because the network isn't working because someone got the mask wrong.
Provides a simple TCP/IP network information.
From David le Roux of Novell Consulting in South Africa in 2002, here's an indispensable tool for all who install and support NBM -- A small, fast IP calculator! (And free. Thank Dave when you see him...)
This utility has been written to provide simple TCP/IP network information.
Install it by unzipping the zip file to a temporary directory, then running the setup.exe
Find the startup link under Start/Programs/Cool Solutions/ and fire it up.
Enter the IP address you would like more information about, then drag the slider to change the sub-net mask until you get the network you need.
This utility was not written to be too controlling regarding the information. Hence the ability to drag the slider over the full range of sub-net bits. IE. Not all subnets may be legal.