Linux® Routing

IPv4 Addressing

Over the years, we’ve all gotten comfortable with good old IP version 4. IPv4 is based on 32-bit host addresses. Addresses are first broken down into the classes A, B, and C, with D kept aside for multicast channels. The address class determines how many bits in the IP address apply to the network number and how many apply to the host number. All subnets made of these networks are of equal size and so on. Each new thing you learn about working with IP v4 lets you add more levels of complexity to your networking setups.

IPv4 Math Review

We’re not going to dwell on IP basics too much here. Most introductory network and Linux books cover that kind of information. In case it’s been a while since you really needed to deal with it, ...