IP addresses can be marked as available, unused or reserved and comments added to each host. Each IP subnet has its own tab, which makes it convenient to keep track of all of your networks. The tool’s filters are also useful features. You can restrict its output to available addresses (by default IPs of hosts that didn’t respond), used addresses (IPs of machines that have responded), and reserved addresses (IPs that you mark as reserved).
This tool can be download from Here:
http://www.solarwinds.com/products/freetools/ip_address_tracker/