The SolarWinds Advanced Subnet Calculator is completely free and fully functional. In fact, it actually delivers four tools in one:

* Address Details - provides forward and reverse DNS resolution, response time, address translation (hexadecimal and binary) and address class information. SolarWinds Advanced Subnet Calculator also supports resolution of IP address owners to aid in managing your network.
* Classful Subnet Creator - calculates subnets based on subnet mask, mask bits, host bits, number of subnets and hosts per subnet. SolarWinds Advanced Subnet Calculator also generates a range of subnets based on these settings.
* CIDR Calculator - includes full support for Classless Inter-Domain Routing (CIDR). Use of CIDR addresses reduce the size of routing tables and make more IP addresses available within organizations. This CIDR classless subnetting feature is particularly useful for ISPs, universities, or corporations with many Class C addresses.
* Subnet Addresses - generates a list of addresses for any subnet, which then becomes the working document from which to assign current and future IP addresses. You can even assign addresses within SolarWinds Advanced Subnet Calculator and then print the worksheets.