I found this three tools are useful for vlsm and for subnet calculation also there lot of ohter tools are there and you will find in my blog also and i have article for this and you can read that blog. But the one thing that i can notice to you that this kind of software dont give me enjoy and i feel bored to use this kind software and i found happiness to calculate subnet and other ip addressing topics using the paper and in pen or by using the power of mind.
You believe that i download this kind of software so many and nothing special in here but sometimes its so useful and i think this is your personal matter how you like softwares personally and how you effectivly use the software and what kind habit you have and all of the things depends on you. Graphical user interface is very good and also a very good solution and we all know that softwares makes our life shortcut and very useful and it reduce lot of time as it so quick and designed for making things easy.... ok guys ...... so download this softwares if you or you can look for ohter so many softwares but these are some one that i find little useful and i know there lot of other related softwares are in online and i think you will find it and will use it for you.