More Subnetting Explained: Howto Subnet Made Easy

Anyone studying for their CCNA needs to know how to subnet backwards and forwards. Here's another informative explanation. See if you can wrap your head around this!
IP subnetting made easy

IP network engineers need a solid understanding of how IP subnetting works--yet the subject is often taught so poorly, students wind up completely baffled. George Ou has developed a simple, graphical approach that explains IP subnetting in a way that finally makes sense.