A subnet visualization chart provides a quick reference for identifying network ranges, subnet masks, and usable host addresses without manual calculation. The chart organizes subnetting by bits borrowed, making it a practical field tool for verifying subnet configurations across any octet.
Visual Subnetting Chart
There is a visual way of being able to subnet, so we're going to take a look at a table that's going to help us visually break things down a little differently. It's something that I introduced towards the end, because you don't want to rely on it. If you're going to take a certification test, you're not going to be able to have any notes or use anything like this when you go in there. But when you're out there in the field and you want to quickly reference something, it is pretty nice to have some sort of visualization chart to do just that.
So this is a visualization chart that really can help us accelerate our process of going through this, or at the very least, this could be just something that we could use to double check our answers. So what does this look like? Number one, this is not the full sheet, so you'd probably want to go and download this sheet. You could just do a Google search for it, or you could use one of my resources by getting onto my courseware. I will have this accessible that you can access.
What we have across the top is how many bits that we're borrowing: one, zero, one, two, three, four, five, six, seven. I didn't include eight, because that's just 255 and everything is individual and it didn't really fit very well on here. Even this seven doesn't fit very well on here. You could use this for any octet — the second, third, or fourth octet — which this would still help you visualize how to break down those individual networks.
We can also see what our subnet mask is going to be. So zero, if we're going to borrow a bit, that's 128, 192, 224, 240, 248, 252, 254. What happens is we have the full range of that octet, it's 0 to 255. So that's the full range of the octet. If you borrow a bit, then it splits it into two ranges, zero through 127, and if you were able to see it, it would have 128 through 255. And then notice that the zero through 127, if we were to split that again, we would be able to split it into 0 through 63 and 64 through 127. If we were able to split that again, we'd have 0 to 31, and this is actually supposed to be a 32 through 63 — that's already corrected on the actual worksheet, I just haven't updated this sheet yet — and then we've got 64 through 95 and 96 through 127.
You can see every time we break this down further, when we borrow another bit, all it's doing is dividing these into more networks. Each one of these is the network range, and then you can break it down even further, and then even further, so far to where we can't really even see what those numbers are. So this is a way to quickly visualize how you would use this.
Let me get some of these marks off here. Let's say I want to have eight networks available to me. Here's where I'd see one, two, three, four, five, six, seven, eight — the rest of the four are down below. So I would want to borrow three bits. There would be my 224, which would be the subnet mask for that, and then I would have how it's all split up. So now I can quickly jump to my answers. I know that the first one here in the range is the network, the last one is the broadcast, and anything in between is going to be a simple calculation to figure out what the usable range is. So this is a quick way to be able to see and visualize all the different networks and how it gets broken apart every time we borrow another bit.
Here's one more example of that. We have a 192.168.0.something, and what we can do is, we need four subnets. If I need four subnets, here's one, two, and then three and four down below, so I want to borrow two bits. So I'll borrow two bits. The address class is a C. I can do a 255.255.255.0. Next, the custom subnet mask is going to be 255.255.255.192. And then total number of subnets, I've got — there's going to be four there, I can just count how many there is, one, two, three, and four. Total number of hosts, so for each of those networks, there's going to be 0 through 63, so total there is 64. Usable hosts is going to be just 62. So there we have it. And then for the rest of it, now I've got my range, and so I know what the network address is, the broadcast, and everything in between.
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