DotNetIP Database is a free application used for tracking v.4 IP subnets and IP addresses. 

Features

• Create Subnets
• Add IP address with Descriptions to subnets
• Subnet Calculator
• Mechanism for ensuring IP and Subnet assigment consitencies.
• Extensive error checking
• Easy to use interface
• Simple to install
• ABSOLUTELY FREE!

Specifications

DotNetIP Database is an ASP.NET with VB.NET code-behind.  It requires IIS and either SQL-SERVER or MSDE.