IP Addressing Fundamentals

0:00All right, as we get started in this particular course, I got to ask you a question. Where are you in your career? And what are your goals in your IT career? Regardless of where you are, maybe you've been on the help desk for a couple of years or so, and you're kind of ready to get off the help desk. I mean, it's a good entry level, but a lot of times we don't want to stay there because we want to move into things that are more advanced. One of those things that's more advanced, server, the server world, systems administration. That's why we're learning more about Server 2025, Active Directory, all that stuff.

0:31Another big part of it though, is understanding networking. And this is going to apply whether you work with Windows Server 2025 as an admin, or whether you move into other parts of IT, like network administration, network knowledge, and a good understanding of these fundamentals is pretty critical to just about everything. I can't remember the last time I worked with a server or really even a client that was strictly cut off from any network. Everything's connected these days. It kind of almost has to be. So this is what we're going to be taking a look at in this particular skill.

1:04We're going to be looking at IP version 4, addressing basics, okay? We're not going to delve all parts of it. We're not going to get into things like custom subnet masking, but we are going to look at the essentials of IP version 4. How do I identify what kind of an address it is? Whether it's a public or a private IP address, that sort of thing. We'll also be taking a look here at IP version 4 classful subnet masks, because you can actually use a subnet mask, which will identify in part what network a specific host belongs to.

1:37And properly subnetting will be pretty significant when it comes to making sure that something is set up properly and that you don't have troubleshooting further on down the road. Also look at IP version 6 addresses. Problem is IP version 4 addresses, well, there's really not as many as we thought there was going to be. And so we had to come up with some solutions. One of those is IP version 6. There's a substantially huge number of addresses available there. And IP version 4 private IP addresses, which is something we can use internally and not really be that concerned about running out of addresses.

2:11So those are some of the things we'll be primarily looking at in this particular skill as we get started in the world of networking.

0:00All right, let's get into it, shall we? So we're going to be taking a look here at IP addressing basics. First thing I want to point out here is that we're really focused on IP version 4 for the majority of what we'll be discussing and what we configure. Reason for that is because internally in most organizations they're still using IP version 4. There is also an IP version 6, which uses a totally different scheme. The addresses look totally different. Everything's different. But internally, as we configure and manage networks and configure our networking services, generally speaking, we work with IP version 4.

0:34We'll get into more details about IP version 6 a little bit later on, but just as we kind of scratch the surface with it, okay? Because again, we primarily do IP version 4. So first thing to understand is that you cannot just assign whatever IP address you feel like, okay? So on a single network, for example, I couldn't have one computer at 25.6.7.8, and then on another computer in that same network, I couldn't put it at 192.16.24.1, okay?

1:04Those hosts are unlikely to communicate with one another. So it has to be set up right, okay? One of the first parts of that is understanding the class of networks. There are three primary classes of networks, and then there's also a fourth one, which is not really used primarily in our discussion, but I'll get to it a little bit later on. So first thing let's understand is the class A network, all right? When you look at these addresses, and we'll get into some more of the details on kind of the mechanics of how all this works out mathematically, but when you look at this just visually, we're seeing decimal numbers here, right?

1:38So this is a decimal number. These are just kind of the numbers you see, one, two, three, four, five, six, seven, eight, nine, and so forth, that are human readable, okay? These are human readable numbers. Your computer will actually see numbers more like this, bunch of ones and zeros, okay? And it's really a string of 32 bits like that. Those are all bits. We're not gonna delve into that quite yet. I'm just gonna start with the human readable side of things, okay, that's easier to make out. So with a class A network, when you look at an IP address on a host, if it starts with any of these numbers, one up through 126, you could just eyeball that and immediately know that that's in a class A network, all right?

2:19Now, without muddying the waters too much, there are ways to cheat that. Just so you know in advance, in case you're thinking ahead of me and you're already familiar with networking, you can use a class A decimal network or a network ID or class A IP address, but you can kind of cheat it by using a class B or more likely a class C subnet mask, okay? So I'm just saying that right from the beginning, but we're gonna work with defaults right now. So yeah, this is the starting octet. These are all what we call octets, okay?

2:50Between the periods, okay? So that's the first octet is right here. Second octet is right here. Third octet right here. Fourth octet right there, okay? In this case, they're all the three remaining ones, they're all zeros. And again, we'll come back to octets and the meaning of that later on, but the significance of that is that there are eight bits, hence the term octet, O-C-T is Latin for eight. I don't know, I'm just saying that because I want it to sound like I went to college. Anyway, I actually think that's true, but those octets are all in binary bits of ones or zeros or whatever, okay?

3:26There's eight of them per octet. We'll look at that again in the next topic as we move on. But by default, and again, these are just the defaults, you can cheat this, but the default subnet mask would be a 255 here. So when you look at a network configuration, for example, you might have a host that has an IP address of, I don't know, 65.1.2.3, okay? That's its IP address. Let me write that down, okay? And it would have a subnet mask of 255.0.0.0, okay?

3:58So that would be how I would configure that. If I were using classful, this is also known as, I don't know if I have it on there, yeah. It's also known as classful subnet masking. In other words, using the default subnet mask. Now, here's another example of one of those IP addresses, right? It's a class A network. There's also, by the way, I should point this out, a 127 in here, which I'll talk about a little bit later on. Technically, that's also class A. It's just that it can't be used to communicate with any other host. So we kind of leave it out of this default class A network. But here's an example.

4:29I might have a host with an IP address of 109.210.27.4, right? It's gonna have, if we're using classful subnet masking, a subnet mask of 255.0.0.0. Now, I will point something out here, okay? With these bits, which again, that'll come to light a little bit more in the next topic. With those bits, we have a division here. So this means that wherever you see a 255 like that, or any number that's not zero, really, that identifies bits that are dedicated to the network, okay?

5:03So in other words, it creates a dividing line right there. Kind of messing it up, but creates a dividing line right there. I guess they're not equally aligned. So that would dedicate this to the host side, okay? And the subnet mask identifies which side belongs to the host. So there are eight bits there on the network side. And again, we're seeing this in decimal, so we don't see bits per se, but that'll come to light next. And then we have 24 bits, because there's eight bits in each octet. Eight times three is 24, right?

5:36So that means that I could have pretty much any other number I want through all of these ranges, for the most part, up to 255. So this could be at the maximum, for example, if I was on a 109 network, that could be 109 dot. And if I took the last available IP address in that whole range, it would be 255.255.254, okay? I don't want to get too confusing about that, but usually we do not use the last 255 all the way to the end, because if it was 255 all the way through the end of that address, that would be what we call a broadcast address, okay?

6:17So we can't really use that for a specific host. All right, so what does this also mean, the 24 bits? Well, let's take a look at this in binary a little bit. And then again, I'm going to address that again on the next topic. But this means that how many networks could I have with an eight bit, 255 is what that is, with an eight bit subnet mask? Well, you have two possibilities in binary, there's a zero or a one. So there's two, and then to the power of eight equals, that means there are 256 possible class A networks out there.

6:55How about the host side? Because if you take a look at this, look, all the rest of these relate to the host. So that would be, you know, eight times three is 24. So let me clear the screen here. Two to the power of 24 equals 16,777,216 hosts that we could have on that network. Now, is that realistic? Not at all. You don't have 16 million ports in your data center, even a big data centers.

7:26I doubt if it's going to have 16 million ports that can even be plugged into. And I'm talking about ethernet ports on like a switch or something. So that's what I was saying earlier. A lot of times we'll cheat this and kind of break it up into what we call custom subnet masking. Okay, so anyway, just put that in your back pocket. We'll come back to it. How about class B? So class B subnet, excuse me, networks, class B networks will start with anywhere between 128 and 191. It will use a default subnet mask of 255.255.0.0, okay?

7:57Which you're going to divide it right in the middle here. Okay, so this one divided over here. This one shifts over an octet and it divides it right here. Here's just an example IP address because it's in this range. So 130.5.6.7, okay? And there would be its subnet mask. Now that's still probably not all that realistic, okay? Because let's go bring our calculator back over here to the power of 16, okay? Because we have two octets on the network side, two octets on the host side.

8:29So on the network side, we could have up to 65,000 networks that we could calculate there. And because it's split in the middle, we can also have potentially up to 65,536 hosts on the host side of things. Again, not a realistic number. Again, even in a big data center, you're still not likely to probably have 65, what'd I say, 65,000? Yeah, 65,536 addresses. So once again, you're probably going to kind of trick that.

9:00But nevertheless, that's the starting point. Unless you know the default classful subnet masks, you can't really customize it later on. You have to start with the classful side of things. All right, what's next? Class C, this is the most common one we'll use. It's the one I use in my own network here. And you'll very commonly see this in, gosh, anywhere, really. But it starts with anywhere between 192 and 223.0.0.0, or dot whatever is what all those zeros mean.

9:31And again, in this case, that would mean that the last possible usable address would likely be 223.255.255. Oops, my pen's doing weird things. Dot 254. That's likely the very last possible address you can use in that range. Here's an example of how that might look. 223.64.32.16. Although, to be realistic, I probably should have put a different address in there because you're more likely to see in things like coffee shops, restaurants, possibly in hotels if it's not too big of a hotel, a home network, small office, home office.

10:12The most common addresses you're gonna see are 192. And by the way, if you're at home right now, you probably have an address that starts with 192. 192.168, that's what it usually starts with. And then from here, a lot of times it'll go to dot one or sometimes dot 100, dot, and then whatever else. So these are the ones you see the most commonly. And this is the subnet mask they use, as I mentioned earlier, 255.255.255.0, also known as a 24-bit subnet mask.

10:43So this is a 24-bit subnet mask. Sometimes you'll see it with a slash notation like that. This is a 16-bit subnet mask. This is an eight-bit subnet mask. That's a slash, I'm not clear on that. So that's a lot of times how you'll see it as well. That's called a CIDR notation. Anyway, now what have we got? Well, every time we shift the network bits over to the right, so we started here, and then here we shifted over another octet. Here we shifted over another octet. Every time you shift over to the right, you lose host bits, right?

11:17But you will gain network bits. So this means that if we're gonna calculate, but that calculator is really huge. Let me shrink that down. It looks like a Fisher-Price calculator or something like that. Anyway, so let's go to, what do we got now? Oh, class C, okay. So I've got 24 bits. The math is gonna be the same here as what I showed you earlier, but 24 bits. So that's gonna be 24 to the power of, no, two to the power of 24, excuse me. And that would be the same number we saw earlier, 16,777,216 possible networks we could work with.

11:52If we're using a class C default subnet mask, classical subnet mask, 255.255.255. How about the host side of things? Well, we're gonna have two to the power of this time, eight, because we only have eight bits on the host side of things. So two to the power of eight equals 256, okay? You might look at that and say, James, weren't you working with an address that ended in 254, and you said that was the maximum you could go, yes, but remember, zero is also a number.

12:24So that also counts. So zero through 255 equals 256 possibilities. Usually we do not use a zero with this classical subnet mask because this identifies the network ID, okay? Network ID. So if I were talking to another administrator and I would say, or maybe we're troubleshooting something, I'd say, okay, so what's your network ID over there? That person would tell me, she'd say 223.64.32.0.

13:01She'd say that was their network ID, and she'd probably put a 24 on the end of that to designate this kind of a subnet mask, okay? So this is not an IP address. This is simply telling me kind of the range, if you wanna put it that way, the range of network addresses that I'm using with that subnet mask. It's getting kind of messy, isn't it? All right, I'm gonna quickly go through the rest of this because I'm taking a little bit of too much time. So the loopback address, this right here, this is simply mostly a troubleshooting tool. It's going to be anything in this class A 127.0.0.0 range.

13:35Do you remember how many possible addresses that is? Yeah, 16,777,000 something addresses. And what is it used for? It is only used to ping your own network device. Okay, let me show you what I mean. So this is on my own computer right here. If I do a ping and use ping to see if something's kind of alive or can respond or whatever, it does not always work. Just FYI, and I'm getting ahead of myself a little bit, doesn't always work when you're trying to reach your actual destination, like something out on the internet, because certain network devices will block ping packets.

14:13All right, but inside the network here, and I'm just trying to see if I have basic IP functionality, I would do a ping 127.0.0.1, and I'm getting answers back. So what that tells me is at least in software, the operating system on my local computer, everything is pinging up and down through the stack, and that's working. This does not validate that the router that's in the server room 100 yards away is working. This does not validate that my switch is working.

14:43This does not validate that I can communicate with other hosts on the network. This only tells me that the basic functionality, it's kind of small, isn't it? Let me zoom in. It only tells me that the basic functionality for IP in software here in my operating system is functional. That's all that means. But that's what we use a loopback address for, is for that basic kind of testing. Now, the reality is, again, because we're using a class A subnet mask on a loopback address, we have all loopback addresses in this entire range right here, okay?

15:14So 16 million ways to ping yourself. So as a quick reference, also down here at the bottom, we've got these references for class A, B, and C, and then there's also this loopback address, which I'm covering up right now. Okay, so FYI, I will also put these down below for you, and they're gonna have a white background because if you wanted to print them out, it'll print out better with a white background than it will with this kind of dark themed background. Otherwise, the information should be the same, and I'll see you in the next video.

0:00Okay, so to be honest, one of the struggles that I had in the previous video, was to kind of switch back and forth between talking about what we call dotted decimal and binary and all of this kind of stuff, okay? Here, we're gonna kind of bring those two worlds together for a little bit of clarity here, okay? So again, we're working with a classful subnet mask, the defaults in other words. And again, with class A, remember we had an eight bit subnet mask, which can be in what we call CIDR notation, like that. CIDR notation would be a slash eight, a slash eight.

0:32And likewise for class B, the CIDR notation would be a slash 16, class C would be a slash 24. Those are all CIDR notations. When you have the network ID followed by a slash eight, 16, 24, something like that, okay? Now, what does that mean? Well, the eight, the slash eight for example, means that it's using eight bits here as the network mask or the subnet mask, okay? So these are dedicated to the network. Anywhere you see a bunch of ones all strung together, that means network.

1:04Anytime you see all these zeros, that means the host side. So if someone shows me an IP address, it looks like this, I don't know, 32.5.6.1 forward slash eight that means that they're telling me they are on a class A default subnet mask, okay? So that's how that's used. Now, the decimal side of things, also known as dotted decimal, is really just for human readable format. Now, this is not really too hard to read.

1:35You can kind of make this out, a bunch of contiguous ones there. But nevertheless, one other thing I should point out there is that notice that they're all contiguous. In other words, it's not a subnet mask of one, zero, one, one, zero, one, one, zero, something like that, okay? It's mixing up zeros and ones like that. That doesn't work, all right? It's all contiguous ones, all contiguous zeros. There's not over here on the host side of things. There's not a zero, one, one, zero, one, one, zero, one or anything like that, all right?

2:07Again, all contiguous ones for the network side, all contiguous zeros for the host side. But again, for us weak-minded humans, it's just easier to read like this. Now, the reality also is, by the way, that your computer doesn't see this broken up with these divisions. Your computer just sees a continuous 32 bits total, all strung together. We divide it up to make it a little bit easier to read, all right? And likewise, over on the dotted decimal side of things, we even separate it with a period here, or a decimal really, the dotted decimals, we're calling that, so that we can break it up a little bit, make it a little more digestible in terms of putting eyes on it and seeing what we're working with.

2:52I mean, without it, we would have something like this, right? It's just, it's not as easy to identify what we're working with there. I mean, is that a 25.50.0.0? What is that? Or .0.0? Who knows? So that's why we put it in like this. So with deliberate action, we put in the dotted decimals there. Each one of these represents the binary side over here on the binary, right? So the 25.50.0.0 is a continuous string of ones in binary format.

3:24Now, it's really beyond my scope here to go into the math of that, but let me do it anyway, just to help make that a little bit more clear. And usually when I teach this in more depth, I write it all out and everything, but in this case, I'm just gonna cheat and use the calculator again. So for this one, I'm gonna change to the programmer version of the calculator here. And if I look at the decimal, if I click on decimal, I don't know if you can see that. Actually, maybe I should make this bigger now. Over here on decimal, that's what I've selected. You can see the little orange line next to it. If I click there, and with this, let me just put in, I don't know, any number, 192, let's say.

3:59Well, what does that equivocate to in binary? We can disregard for right now hex and octets and whatever that is, but in binary, that would be like this, right? 1100000, all right? Let's put another number in, 178, let's do that one. I'm just making a number up. With that one, the decimal is obviously 178, but in binary, that appears like this. Now, how do we make sense of that? So how would we convert that if we wanted to just do it mentally and not use the calculator here?

4:31Let me show you. I went ahead and pasted this in here to make it a little bit easier. What was our number, by the way? I just saw it, it was in the calculator, 178, okay. So how would I calculate that just doing that mentally here? Well, what I wanna do is to come up with some combination of all of these numbers that adds up to 178, okay? None of these numbers are bigger than 178, so I can start with the largest one, that would be a 128. And I can put a one or a zero here. Anytime I put a one in there, that means I will count that number. Anytime I put a zero in, that means I will disregard that number, okay?

5:04So if I had a one and a zero, that means I'll count the 128, but I will not count the 64. I think it will count the 32. You just gotta do the math in your head a little bit. Then I can add the 16. So what do we got here? 128 plus 32 is 160, right? Yeah, and I'm trying to get to 178. So 160, this would give me 176. So I should only need two more to get to 178, right? That means I'll go a one there. That means the rest of these will be zeros. So what this is telling me is, anytime I see a one, I will count the number, okay?

5:38That is underneath it. So I'm counting up 128 plus 32 plus 16 plus two equals 178, okay? So that's how we convert from binary to decimal, all right? Now we don't need to practice that a lot or anything. I'm just showing that right now so you can kind of get a comprehension for how we flip back and forth between the two numbers. Let's do another one just for a grins though.

6:08Let's just put the number. Actually, you can do this on your own too. Just pick a number out of the air and kind of use this little chart here to figure it out. Let's do 241, okay? So 241, I know I can use 128. I wanna use the larger numbers when possible. And by the way, there are no two ways to come up with this. Okay, there's only one combination that will work. So what did I just say? I can't remember what number I just said. Let's just go with 197, okay? So I'm gonna say, I'll write it down. 197, all right?

6:39So 128 plus 64, I'm pretty sure that would give me 192, right, 192, yeah. So I'm not quite at 197 yet. What else do I need? 192 and 197, the difference is five, so I need five more. So I need a four and a one, that's a total of five, right? So that would be like this. That means that the binary equivalent of 197 would be 11000101, right?

7:11All of this right here, okay? So that's all I'm gonna do right there. We don't wanna get into that too much more depth right now. I just wanted you to see, besides just working with the Classful Subnet Masks, how I can use binary slash decimal conversions there using something like this to figure out what it would look like in binary. So the decimal is easy, right? It's a conversion into binary that we have to kind of twist our brains around and figure out how to use things like this, right? Anyway, you see the rest of the equivalents down here, and that's just there for your reference.

7:45Also, I should point out, there's also a Class D, we don't really talk about it much, and it's called multicasting. It's a multicasting range of addresses. The purpose of it is that I can send, you can see right here, one stream of data to multiple recipients simultaneously. So this can be used for like, maybe you have a LAN party, you know, a gaming, several people over and you're all playing games, we'll very likely be using some form of multicasting. This does not usually work on the internet, by the way, directly at least, maybe it would work, but I know that services like Zoom, they use their own thing, they don't use this.

8:22I don't think that Google Meet uses this either. There's not generally an internet thing. What else would use it? Apple TV, Roku, a lot of those kinds of things will do multicast. Another thing you could use it for, by the way, would be if I had a server here that was in a distribution server of some kind, we're issuing software from it, we're installing operating systems, then it can send a stream of data to three separate hosts, all at the same one, maybe it's transferring files to each of them, rather than sending a separate send to each host separately and consuming more network bandwidth, with multicasting, I can send the same stream of data simultaneously to all three of those.

9:04And of course that can scale up to a lot more than three, but that's the basic idea for how that works. All right, that's it. Classful subnet masking, and a little bit sprinkled in there of converting from decimal to binary.

0:00All right. Did you ever run into a situation where you ran low on something like money, for example? The other night, I decided to take my wife to a nice romantic dinner. I thought I was being quite nice. Anyway, took her to a nice romantic dinner, and I looked at the total of how much it was going to cost. It was $36. That's what I get for ordering two Big Macs and two hot fudge sundaes in combo meals. I can't remember what my wife ate, but that's what I ate. Anyway, it added up to more than I thought I was going to add up to.

0:32Well, the same thing has happened with IP addresses. The IP version 4 addresses that we have, well, there's about 4 billion of those addresses, but because of the way they were carved out and the way they were distributed and everything like that, let me show you, it turned out that all of the addresses got consumed. They were just wasted, really. They were not very efficiently divided up. That's because the IANA, which is the Internet Assigned Numbering Authority, it's an organization that divides up the addresses. They didn't realize how big the internet was going to get. Nobody really did. So I don't really blame them for that.

1:05But where did all the addresses go? I'll put this link down below so you can see this for yourself if you want. But this is where they all went. These are the class A address blocks that got distributed. Look, US military, the Department of Defense, which is now the Department of War, 201 million addresses just for the Department of War. Now, that kind of makes sense in a way because DARPA was originally a military initiative and it was driven by military needs. And that's part of what all this is relating to. The internet was originally designed primarily as a redundant communications network for the military. So I guess that makes sense.

1:44Now, Department of Defense, they have 2.89 million employees, civilian and military. I don't even think that includes contractors. So yeah, they're a big organization. I think they're the biggest organization in the world, IT organization in the world. But you see a lot of other technical companies here and big companies like Hewlett Packard and Apple. And I think there's a car maker in here as well. Yeah, Ford. So you can see they've all got millions of addresses. MIT is in here. They've got 16 million addresses. But because of the way it was all divided up, they all got consumed much faster than anybody would have anticipated. And that's why we went to something called, or it is the RFC 1918. RFC is request for comments. And that's where you can kind of submit papers. You have to have some credibility like all of these brainiacs over here. And you can see there's people from Cisco and Chrysler and RIPE, which is a regional internet authority and stuff like that. Anyway, they came up with RFC 1918. And this allocates, where is it? Well, I just saw it. There it is, private addresses like this. So if you see addresses that start with any of these numbers, those are going to be the private IP addresses

2:59that you can use internally. They don't route on the internet. So you can't just put a 10 dot address directly on the internet. It won't go anywhere. The routers on the internet will just drop it immediately. There are ways around that, which I won't get into right now, primarily through NAT, which is Network Address Translation and or PAT, which is Port Address Translation. And most of the time we're actually using Port Address Translation. But when it comes to doling out addresses, one of the other things that they come up with is IP version six. This is to help guarantee that we don't run out of addresses in the future. And we're not going to touch on IPv6 much here because most organizations are still using IP version four, but I want you to be familiar with it. And again, I'm not going to read everything that's on this, but I will link it down below for your own reference. There are three main address types that you can use. One is Unicast right here. And this is kind of a overall type of an address type. Global Unicast right here is a subset of Unicast. And they also use prefixes just like we do in IP version four.

4:02But the main idea that I want to get to here is IP version six has substantially more addresses than we do in IP version four. In fact, it's 128-bit address. So let's take a look. With IP version four, we had two to the power of 32. And we can't use them all, but conceivably that's about 4 billion addresses, right? If we take a look at two to the power of IP version six addresses, which is 128 bits, that gives us whatever that is, which is actually, that's 340 duo-decentillion addresses. Now I've heard that compared and expressed a number of ways. You can Google it or use some AI if you want to try to make a comparison. One of the comparisons I saw said that if you took every atom on the face of the earth times 10, that would be about 340 duo-decentillion atoms. Okay. Wow. So that's going to take a lot. It's kind of hard to conceive that we would ever consume that many. But then again, people that say that have probably never seen my McDonald's bill. Okay. Anyway, that's kind of keeping an eye on the future. Now, most organizations will still use IP version four. That's why we've got this RFC 1918 that I was referencing a little

5:20while ago. So all I want you to know for now is if you just eyeball an IP address and it starts with one of these ranges, you can look at it and immediately say, without doing any math or calculations or anything, you can immediately say, oh, well, that's a RFC 1918. That's a private IP address is what we usually say. And we have class A, class B, and class C, and we have the same numbers here as we did in the address ranges I showed you earlier for IP version. So again, these are only usable for internal network use. So you'll see them in coffee shops, probably your own home, internet router has addresses that are being doled out in this address range. It might seem in hotels, unless it's a bigger hotel, it might be something different. But anyway, yeah, you will still see that. It'll still be an address if it's a bigger hotel with a lot of addresses that it needs. It might use something like this, because you're not going to have still 65,000 or a million addresses on a single network. You can have something like most organizations, like home routers and stuff will be 192.168.100 or 1.0.1.1.

6:28And that's usually a 24-bit subnet mask. Remember, 24-bit subnet mask means you're going to have about 254 usable addresses. So if you're in a bigger hotel, which needs more than 254 addresses, maybe they're going to be using something in the 172.16 address range instead, or they'll use multiple 192.168 addresses. So anyway, that's the basic idea there. But these are used internally, and they help us to expand and kind of almost indefinitely procrastinate our progression to moving into IP version 6, because once again, most organizations will still use IP version 4 internally. The exception would be if someone wants, if an organization wants to transition to IP version 6, there's a lot of things there that could be used to transition to Rado. There's a dual stack where you'll have both. I can't remember if I showed you this. Let me clear the screen here and show you. IP config, all. And you can see here that in my, I've got more going on here than most people will have, because I have a lot of adapters installed. But anyway, there's an IPv6 address. You can tell that because it says IPv6 right there. But even if you didn't see that, you can just eyeball this and look at the length of that. It's a hex number. So in IP version 4, like I have right here and right here, notice it's only decimals. These are hex addresses

7:50which use letters in them as well. A through F could be used. You won't see a Z or a P or an R or something like that. A through F could also be in this. Anyway, just wanted to get an idea for when you eyeball an IP address, how you can kind of get a comprehension of what's going on with and what kind of an address it is.

0:00All right, let's go ahead and take a look at some of these validation questions and get an idea for what we've learned here, okay? First of all, with validation, what is the primary reason for the development of IP version six, okay? Let's just start at the bottom. How about to simplify the IP address structure for easier human readability? That's exactly what it is not, okay? It is not more readable. It's actually harder to read in most ways, but it does solve some problems that we come up against.

0:30And it's kind of a necessary evil, even though it's a little bit harder to read in some ways. To replace IPv4 due to its inefficiency in routing. No, that's not true either. We haven't really brought up routing, but IP version four does route pretty well. And there are a lot of different routing protocols that can route it just fine. Although IP version six has some additional innovations as well. But that's not the reason why we have IPv6. How about this one? Improved security features over IPv4. Actually, it is also more secure, I have to say that.

1:02We didn't discuss that though. That's not part of the material, but there are built-in security measures with IP version six that protect its traffic better than IP version four. Although again, since we didn't discuss it, that won't be a right answer for this. Here we can say to provide a larger address space than IPv4. Preventing future address exhaustion. At least in the foreseeable future, yes. It's a huge address space. All right, next one. What does a slash eight, for example, forward slash eight insider notation indicate about a subnet mask?

1:35Let's start at the bottom. It indicates a class C subnet mask. Well, do you remember what a class C subnet mask would be? 255.255.255.0. Remember each one of those 255 represents an eight bit octet. So eight times three would be 24, okay? So that could not be the correct answer, okay? Unless it was asking for slash 24, then that would be right, but it's not, okay? How about this? Let's look for an eight here at the top. It uses eight bits for the host portion of the address.

2:07Hmm, sounds right initially because it says eight, but remember the forward slash eight refers to network bits, not host bits, okay? How about this? Indicates a class B subnet mask. No, you remember class B subnet masks are 255.255. Which in binary would be 16. So that'd be a forward slash 16 for that one. How about this? It uses 16 bits for the network portion of the address. Nope, that's exactly what that's not saying.

2:37That's saying it uses eight bits for the network portion of the address. So there we have it with that one. Which of the following IP address ranges could be used for class A networks, okay? First, let's start at the top here. 128 to 191.255.0.0, hmm. Well, if you remember the range of IP address of IP version four class A addresses, that's not in that range, okay? I'll make this one simple.

3:07Remember it starts at one and it ends at 126. As a caveat to that, I can't remember if I mentioned the material or not. 127 is a loopback address, is technically a class A address. It just can't communicate with any other system. So that's why we don't usually include it in that discussion. How about this one? 192, whatever, to 223.255.255.0. Nope, again, that's not in the class A range. That would actually be a class C address range, okay?

3:38How about this one? 224.0.0.0 to 239. all of that, okay? Well, remember that is actually our multicast address, class D, okay? So that leaves us with this one, which is also just the correct answer. One, whatever, through 126, whatever, okay? That would be the correct answer for that last one. And that concludes this particular skill. I'll see you in the next one.