For IPv4, try this...

Manoj,If you are looking for help remembering the binary math required to do subnetting for IPv4, than while I strongly encourage spending time to learn how to do logical anding with the binary octets, however, I recommend creating your own cheatsheet.Here are two examples I found:http://www.subnetonline.com/pages/references/ipv4-cheat-sheet.phphttp://www.quest4.org/ccna/subnet_cheat_sheet.htmThe second one above, is basically what I learned to use, and just like the author of that page, I learned to use it in a Cisco class, so I might call it the "cisco" method. Once I learned it, for every ip address space test or problem I had to solve, I used to write out this 3x9 table (matrix) with ascending powers of 2 from zero to eight, descending subnet mask values, then descending powers of 2 from eight to zero. By following the instructions for use found in that post, your subnetting accuracy and time to compute should both improve such that after awhile you won't even need the cheatsheet.I hope this helps.Steve