Private IP's VS. Public IP's

NEW Cisco CCNA IPv4 Course! Introduction to Basic Router Configurations and IP's
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Alrighty, welcome, welcome. Now we're going to do private versus public IPs. Yes, indeed, private IP addresses. They're not routable on the internet, so you don't put a private IP address on an interface that's plugged in to a public interface, because it ain't gonna work. Okay, that's why we use Nat to translate Yes, from private to public. Alright.

Therefore, internal use only not used, but you it is used or not used. You only Okay, internal use only. And they're the chunks of addresses are chosen from the A, B and C, the powers that be said, Hey, we're gonna take a chunk out of the a, like a chunk out of the B, take a chunk out of the C, we're going to use it for internal purposes only. So you guys can do whatever you want with that. Okay, that's a private IP address public addresses cost money. Okay, you have to purchase it.

And that gives you something to think about when you're talking about Nat. Because if you do static Nat, one to one mapping 1000 IP, I mean 1000 hosts need to get out to the internet only thousand IPS, money, dynamic Nat. Ah, easier setup, but I still need 1000 IPS. Forget all that I'm gonna do. I'm gonna do not overload pack, one IP address can handle 65,000 plus people, right? Cool.

That's the way to go. Right? Because this money, you got to purchase these public IP addresses from your providers. Right? You don't want to do that. You don't want to do that.

Okay, so that's what we have not try and minimize the cost. Okay, but not so much where your network goes. Okay, so let's go to lab and get this done. We'll go back. Welcome back. All right.

We're now in the private IP address range law lab. It's basically Just a notepad and I went ahead and put in the actual classes that you need to be aware of, and the range of this and default mass. Now you can see that class A, it's using from 10 001 to 10, two divided by two to four. So the entire 10 range is taken for internal addresses, they're not routable private IP addresses, not routable. As I said previously, they are not routable on the internet, okay. That's why we use that.

Okay, so, anything that starts with 10, again, the whole class A is 10. They took the whole 10 range and made it for class A, and obviously, these are the default math that we use. Okay. This one here is 172 16. Okay. 231 Interesting.

How do they do that? Okay. All right, and then 2425 but we'll get to subnetting but yeah, that because this could be either 16 or 12 actually, or 12 I'm not gonna put that there I'm gonna confuse you because this will be the answer you give in an examination, but the reality is they've asked me Hey, how did you come up with these numbers all First of all, I didn't come up with these numbers. Second of all, this is how they came up with it. All right, do a little research a little hunting and Cisco Academy books will tell you exactly the 16 to 31 how they came about it as really a site or tool that they use. Okay, I started to get that but we got to somebody will look at Okay, and then look at 192 168 for a class See, when I to 168 192 168 so I need there's 192 168 is private as internal, right?

And obviously they go from zero to 250 505-250-4255 Okay, All righty, this would be the broadcast, it has to be five to five, and then you use the default mask. And again, this is one that's also kind of, hey, how did they decide is 192 168? Because it was 192 169. That's public. Over here, if it's 172 15, or 172 30 is public, I mean, 32 is public. So here if it's 191, or if it's 169, then Okay, then it's public.

The number is 182 168. So, it looks like the line has been drawn right there. Right? And here, it looks like a line really. You're playing around somewhere in here. Okay, but we'll talk about that.

But this is what the private IP address range looks like. Okay, that's what it looks like there cider and dvn right, or dotted decimal numbering. There's something That's very basic, something that you commit to memory, you would ask for this, as is, as you see it right there on the screen. Once you get to somebody, I'll go deeper as far as the B and C, and they're not their actual, but how they came up with. Why did they draw the line there? All right, why did they choose that?

But all this is it public addresses get assigned to you by your providers, your providers, you purchase public addresses, you pay for it, right? We talked about it already. So public addresses are for you to be able to get out on the internet. Now, you may have firewalls or you know, that are far enough internet firewalls are out there already. Okay. You may have a lot of servers that are public servers, you know, like web servers, what have you.

So that when your public IP address, okay, a public IP address. So those are the differences, right? So anything that's not here is a public IP address. And there's not here is not a public IP address. And you need to get it all the way live in North America from error. Okay, from the registry, they give it to us, right?

And everybody in their particular section we're part of the world have their or Aaron, should we say that gives them their internet Association, right that gives them or their providers that give them their IP, public IP addressing scheme. But this they said, Hey, the powers that be said, we're going to take a chunk out of class A Class B and Class C, and we'll make it private, we'll make it internal. So they can do whatever they need to do internally. This is good to know because you not only for testing purposes, but we talked already about planning. Okay, you need to plan you need to know how much they hold, you need to know who you are their lines, right? So you don't run out of private IP addresses.

You may say, Come on last who's gonna run out of private IP addresses? Well, I can tell you why while teaching in the classroom in one of the many schools that I taught at a consultant that was one of my students came up to me said, Hey, one of my clients ran out of private IP address. Classy It was a class he ran Oh private IP addresses. Well, his planning wasn't very good Wasn't he didn't know that he was going to expand that far. Why are you going to sell so short is like you You know, you start up a company you buy a four port switch. That's it.

That's all you're gonna have. You know, your dentist office or you know, your you may grow. What's a big deal? Buy yourself a 24 port switch. So what you know, I mean, why are you going to six ports? I mean, come on.

Seriously. You're being frugal at this point. So get yourself a nice 24 per switch or if you're gonna be no you know, girl, don't incident turtle class be the bad thing. Once you learn how to summarize. All the I'll show you how to save on sending information to your core routers. Alright, but other than that, yeah, be careful.

You need to know this. You need to know there's only Very basic, and they're probably going to ask you this on the CCNA. But as an IT professional, yeah, you need to know this if you don't know this, wow. Okay, but yeah, know this alright, but that's it. That is your private IP address range. See you later.

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