Subnet Calculator - Version 2.1.0 The Subnet Calculator (SC) by Dx21 is a utility designed to assist in the discovery of appropriate subnetting schemes for your network. The SC can assist you in finding the right subnet mask for your needs, displaying information about Class A, B and C networks, segment information for each Subnet Mask, along with giving you the ability to test a range of IP addresses for a network presence. Discovered information can be exported to a text file or a CSV file for import into a database or spreadsheet program. Includes links to various web documents to assist in the education of TCP/IP.