Bro, figure.
It out. Now Michael knows how to subnet, but this,
this stumped him because this particular problem requires you to subnet and
reverse or you know, you know what I mean? Or do you, I don't know.
And that's what I'm going to show you in this video.
How to reverse subnet or backwards subnet. And by the way,
that was a subnetting problem I showed you in the last episode.
Were you able to solve it? It's a hard one, right?
And shout out to Boes on software for sponsoring this entire series and
providing that amazing question. So real quick,
you may not suck at Subnetting anymore, you're pretty good, right?
But things like this may have you scratching your head just when you feel like
you're getting the hang of it, this happens. And that's okay.
That's the point of this video. Subnetting again, is a skill.
You have to keep practicing.
You're gonna have weird things hit you and you'll be like, what is that doing?
Remember when I said I knew how to subnet ? Because if I'm being honest,
I don't know what like that thing is right there. I can't do it.
I'm not smart like you, Chuck.
Do you suck at Subnetting? I suck at Subnetting. Say I still suck at Subnetting.
I still suck at.
Subnetting. So we're gonna walk through that. And by the way, Michael,
by the end of this video, we'll figure this out.
He's gonna do this cuz he'll watch this video, right Michael? Yes.
So get your copy ready.
I'm gonna walk you through exactly how you can reverse subnet and also why you
might need to, like what's the reason. So real quick, do this.
Sip your copy first
Quick on your computer. Want your command prompt terminal, whatever you got,
and type in IP config or i f config if you're on Mac and Linux.
And let's see your IP address configuration.
And maybe if you don't have that right now, just check your phone.
Go to settings now, whatever you have, write it down.
We'll touch on that here in a moment. The first look at mine here,
yours should look something like this. Well kind of,
you should have an IP address there. Here's the IP address,
here's the subnet mask, and here's the default gateway. With this information,
I want you to figure out and tell me the network address, the broadcast address,
and the network range.
Now this does call for reverse subnetting because notice the subnetting has
already been done. Like the network configuration's there.
You have to get in here and figure out who did this .
Well why did you do this? Because honestly, right now there's a problem.
This host can't ping anything. They have no network access.
They put a ticket in and you're gonna have to solve it.
This is a common issue you might see. So Beatrice over here,
which is the host we just looked at,
she can't ping or reach Bernard Hack well or really anything. And by the way,
I spun this network up in seconds. Thanks to Boon NetSim.
If you wanna play with this yourself, check it out. Link below.
So let's reverse subnet this. Let's see what's wrong with Beatrice's IP address.
And I know some of you're looking at this and going, it's pretty obvious, Chuck,
is it ? Let's try it out real quick.
Now the good news is that you already have the skills to do this.
You just kind of have to approach it in a different way.
And it's actually not too bad. It's pretty easy.
And most of what we were doing was figuring out the subnet mask we already had.
That half the work is already done for us.
So we can remove steps one and two and jump right into step three.
But not without a bit of help from our friend Nosferatu.
We first have to convert our subnet mask from decimal to binary to the language
that our computer loves. Just they love it.
So our mask is two 5.2552 40.0.
So we have our chart nosferatu, go ahead and hit the lights.
Let's convert this to binary. And there is our subnet mask in binary.
Thank you Nosferatu. And since we're here, what is the subnet mask?
Insider notation might recall that all we have to do is count the network bits,
which are the contiguous ones. How many we got?
8, 16, 17, 18, 19, 20.
We got us to slash 20 over here. So step three , find the increment.
Let's go ahead and find that right now.
The increment is the last network bit in our subnet mask. Here he is right here.
If we throw that octet onto our nosferatu chart, Nosferatu, help us out please.
We can see our last network bit represents 16. 16 is our increment.
And with that we can now build our network ranges. Okay, creating our networks.
Here's our IP address, there's the mask. Let's get to work.
The first network we know will be 1 72 because all of the bits are network bits,
meaning this guy stays, same goes four 17.
The second octet is also all network bits.
The third octet is where things get interesting.
We'll start at zero and also another zero and the range, where's that gonna go?
Well, our increment is 16, so it'll be 1 72, 17.
And see this is where we're gonna have to actually increment.
It's in our third octet. You're used to class C addresses, right?
So you're used to incrementing in the fourth octet. No,
we're gonna do it here in the third octet. Moving up 16,
we're gonna have 15 2, 5 5.
Let's do two or three more just to hit this home. Starting again,
we got 1, 7, 2, 17, 16, 0
through 1, 7 2, 17, 31
0.25. Now shortcut is you don't have to do the entire range.
You can just do the uh, network address. Just keep incrementing 32.0,
64.0 and we'll stop there. So real quick,
where does this IP address beatrice's IP address?
Which network does this live in? Well obviously not the first one,
but it is nestled safely inside the second network. ,
you may have noticed that's a lot of IP addresses.
You normally won't have a network that big in the real world.
That would be a disaster. But this is just fun for examples,
it's making you think. So Beatrice is in this network.
The first question off the bat, is beatrice's IP address valid?
Like is it actually a real IP address? And some of you may have thought,
well of course not. It ends in 2 55 and that's a broadcast address,
not in this network, no.
See the broadcast address for a Beatrice's network is this guy right here,
the last IP address in her network.
It feels weird because we're incrementing in the third octet.
So that's why it is doing that.
But just know if you see 2 55 or even zero as the IP address,
those can be valid. Don't immediately discount those.
If the network's big enough, it can contain that. So yes, beatrice's IP address,
that's a tongue twister is valid, but she still has a problem, right?
She still can't ping anything, she can't reach anything. So what's the problem?
Well,
let's see what network Bernard hack well's in because their IP addresses are
pretty different.
Like he's in 12 in the third octet and Beatrice is in 16.
They're basically on different planets.
So let's figure out which network Bernard Hack was is in.
It looks like he's in the first one, right?
And there we're starting to see our problem.
Beatrice and Bernard are in completely different networks.
And looking at her diagram,
it seems like they should have been in the same network because the router,
what network is he in? He's in Bernard's network.
And if you look back at Beatrice's IP configuration, her default gateway,
her router is 1 7 2 17 0 1. No wonder she can't get to anything,
not even the internet because her default gateway isn't even in her network.
She's lost.
So I hope that illustrates why it will be helpful to reverse engineer a subnet,
which you just did, right? And we figured out our our range.
We got our broadcast address, our subnet address, or our network address.
And just like that, you learn the superpower. Coffee break for you
never checked out coffee. This is the pseudo blend by the way.
It's kind of my favorite right now. It's amazing. Oh,
it's not a blend by the way. It's a single origin from Nicaragua.
It's fantastic. So now that you know how to reverse subnet, reverse your subnet.
Remember earlier I told you to check your command prompt terminal,
whatever it was and see what IP address you had configured and do the same thing
on your phone. What's your network address? What's your broadcast address?
What network range are you on? Figure it out. In fact, comment below,
I would love just to see my comments filled with IP addresses and network ranges
and things. What can be better than that? What's YouTube gonna do with that?
I don't know. And also,
now that you know how to reverse subnet the problem we had originally Michael's
problem. I think you can do this now. Try it out. Go ahead, pause the video,
unpause, comment below with your answer. And actually right now,
let's go see if Michael can do it because I did have him watch this video.
And hopefully Michael, you learned it right? I.
Officially don't suck at some netting anymore.
Now shout out to boes on software for sponsoring this entire CCNA series and
making it free here on YouTube. They provided this excellent exam question,
which is a question you'll probably see, or at least like this on the real exam,
the ccna. Now lemme be clear,
you won't see this exact one that's called cheating,
but you will see stuff like this.
So Boon has practice exams and also the lab environment.
I showed you earlier how I set up my network that's built to help you learn
Cisco networking, to put to practice,
to put to real world what you're learning for the cna.
So if you're really seriously about getting your CCNA boon,
you want their net sim, you want their xm, check it out. Link below.
If anything,
just show them some love for making this series possible and supporting what I
do here. I love those guys. Now I do have one last question for you.
Can you subnet a subnet? A subnet? A subnet?
That's what we're doing in the next episode. Buckley, your seatbelt.
This never ends, right?