CCENT Cisco Certified Entry Networking Technician Study Guide: (ICND1 Exam 640-822), 2nd Edition

Subnetting Basics

In Chapter 2, “Internet Protocols,” you learned how to define and find the valid host ranges used in a Class A, Class B, and Class C network address by turning the host bits all off and then all on. This is very good, but here's the catch: you were defining only one network. What happens if you wanted to take one network address and create six networks from it? You would have to do something called subnetting, because that's what allows you to take one larger network and break it into a bunch of smaller networks.

There are loads of reasons in favor of subnetting, including the following benefits:

Reduced Network Traffic We all appreciate less traffic of any kind. Networks are no different. Without trusty routers, packet traffic ...