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# Course: IP Version 4 Addressing And Subnetting Deep Dive (Part 5)

joshman
69

Hello and welcome, I am currently working on a video course 'addressing' IP version 4, and I've decided to post my slides and scripts here on STEEM as I go along. I appreciate any feedback or suggestions, or if you are new to the world of computer networking, I hope you enjoy them!

Here is part 5 of a multi-part series. How many parts will there be? I have no idea because I am posting them as I go along.

In our example we have a /24 or Class C private block of 192.168.42.0. The first address, the .0 is the network address, and the last address, the .255 is the broadcast. The leaves .1 to .254 as useable addresses.

Now that we understand the addressing limitations within a single network block, we can move on to subnetting.

Let’s say we are allocated a full Class C network address, also referred to as a /24 in CIDR notation. That /24 has 24 bits in the subnet mask and network portion of the address, and 8 bits in the host portion. Using subnetting, we can subdivide this network into two or more smaller blocks called subnets. We do this by adding bits to the subnet mask to create a subnet address. This borrows bits from the original host address, and dedicates them to subnetting. This lowers the number of available host address while creating subnetworks.

Continuing on down the line, we subtract a bit and the available hosts is reduced in half again and again until we get past the /30 range. /31 address is unique application of subnetting, as there are no network or broadcast addresses. The /32 address is considered a host address, or host route, because it represents just a single IP address. We will discuss the application of both of these address types later on.

As promised, let’s take a look at the equation for finding the number of available hosts on a subnet.

It is simply 2 to the power of n minus 2, where:

• 2 represents the possible binary numbers of one and zero
• n represents number of host bits or 32 minus the number of bits in the subnet mask