4.6 What is Logical or IP Addressing

0:00 Friends, in this video I am going to discuss a very important point. First of all I will talk about logical address and IP address, what is basically the difference between IP version 4 and 6. What are these properties of logical addresses, which are unique and universal? What is the understanding of binary notation and dotted decimal notation? What is classful addressing and what do the classes A B C D E mean in classful address? All these topics, whether it is your university exam, your viva, placements, campus exam or GATE NET, all these topics hold a lot of importance in IP. I will discuss each topic in detail one by one. So let us understand now what is logical addressing or IP addressing. For example, if we have to send a letter anywhere in India, what has the postal department

0:46 done? Every location has been given some pin numbers, right? What is the post office number here? What is the pin here? We ask, in the same way, what is the internet? Friends, the internet is a network. It is a very big network which has covered the whole world and who carries data on the internet, so the most important protocol of the network layer is called Internet Protocol which is called IP. There are two versions of IP, right now I will talk about IP version four and IP version six, so here IP version four is written. In the default case we will assume IP version four, so this is a protocol, what does it do, it gives a 32 bit address to every device that wants to be connected on the internet, 32 bit address, then you understand how many combinations will be formed from 32 bits, the combination will be 2 to the power of 32, so if I convert it into decimal

1:32 then it becomes approximately 429 crore 4967 296, although there are some restrictions in it, every address cannot be used, but still this number is very big and IP version 4 says that with the help of this address I can find any device on the internet and with its help we can communicate with any device. Okay, so the first question was what is logical address sir, internet protocol allocates an address to every device which is connected to internet, we call it logical address or sometimes IP address in short, however now see, understand a problem, 2nd to 32, what I am saying is about 450 crores, it looks like a lot, friend, it's fun

2:19 but already the world population is about 8 billion, right now when I am making a video, you can already imagine that we have almost double the population and in the coming time you can see that as internet expands and things move forward, will one person's work be done in one IP, no, my phone also wants to be connected to internet, wants to be an AC, wants to be a washing machine, wants to be a doorbell of the house, like this, so we have already found a solution to this problem and we have launched an advanced version of IP version 4, which is IP version 6 and look what mind has been put into IP In version 4, the length was of 32 bits, right? Now I thought, we will make 32 bits into 33, 34, 64, and if we double it, it may still fall short after 200, 400, 500 years. So

3:06 what did the brothers do? They directly took the length and made it 128. But some people will think, Sir, where did the six and five go after four? Yes, we skipped the five and directly reached si. And this is like how many combinations will be formed, 2nd to the power 128. Even if I tell it in decimal, then after 3.4, you can put 38 zeros, 38 zeros. There will be so many addresses, so this problem kind of got solved forever. So the first problem or the first idea is clear to us. IP Internet Protocol or the logical address, Sir, we call that address, the address that we need through which we can communicate any data on the internet. Now I will come to my second point, which is unique and universal. Now What is this story? Look, the address of the Internet Protocol, which

3:51 we call IP address, has two properties, that it will be unique as well as universal. Now what does this mean? Can there be any such device or address on the Internet that is only with two devices? No, the IP address that I have is only with me, it will not be with any other device. That is called uniconnect. What will happen is that I can find any device unique with the help of that address. That address is unique. Only one person has that address. The second important thing is that if any device wants to connect on the universal Internet, does it have any option or is Internet Protocol the only option? And it must have an IP address. It must have acceptability. It's like a passport. Now you

4:36 understand that if I identify myself in India, Identity Identity Identity it. So the passport number that I have will not be with anyone in the whole world, not just in the country. Point number one, point number two, if I have to travel internationally, all countries should use any local policy within their network. We don't have any problem but internationally everybody will follow the passport. Everybody will issue passport to their citizen who wants to go out of the country and if a citizen of another country comes back then he will be asked for his passport. So unique and universal means that everybody will have a unique IP address. Point number one, everybody will follow this IP address. There will be no such

5:22 device which will say that I am connected to the internet but I do n't have an IP address. One small thing here and this IP address is not the property of any device, what is the meaning of connection. For example, you can understand this car. See, the car has a number plate, right? Now the number plate can change with time but normally it doesn't change but imagine, I will explain to you. Suppose a car is registered in Delhi and the person gets transferred and he wants to stay in Kerala for say 5-10 years or is going to Kerala, then he will do one thing that he will surrender this number plate in Delhi and can go and get a new Kerala number plate for some time. You can go for it but normally if people travel for a long time then they leave this number plate with them and go there and

6:08 get a new number plate. Some people's number plate is very lucky. It means that it will be a car or a scooter. Suppose if you buy a car after a scooter then the same number plate is used on the car as well. You have to go there and do some formalities. So it is like this. So number plate is a registration which can be changed later. Similarly, IP address is the name of connection. Today you are connected to the internet. You will get an IP address. If you want to connect again after 4 hours or it may happen that your IP address changes but both these properties of universal and unique will still remain. Okay, the next point is notations. Now what are these notations? See, there are two ways to represent any IP number. One we call it binary notation and the other we call it dotted decimal notation. Right now we are already saying that it is a 32 bit number. So either 01 01, whatever

6:55 your exact number is, 32. times you can write it now obviously it will be a little difficult to write like this but still what is the organization in this these eight bits so we can assume four sections of eight bits each eight bits we call eight bits as one byte here we call it octets means what are one octets and whatever will be its values you can write that but obviously working with these numbers on day to day basis you know doing research on these will become very difficult 32 number of humans are not very good with numbers specially binary numbers because it will become very long so what is another notation which we call dotted decimal notation where what do we do this eight bit because if we take out a 32 bit decimal number in it will become very big so what do we do is we convert eight bits

7:42 into different decimals so suppose this is a number whose decimal value will be 172 its value will be 16 254 and 1 so although this is a common thing you people have also seen Sometimes you must have seen such an IP address. If someone asks what is your IP address, then normally we answer like this, like 170 2.1.2 4.1, right? But in this we will obviously not say 0011 00. If you say this then the matter is resolved. There are two understandings of binary notation, where it is written in 0011, and dotted decimal, where it is written like this. There are some more additional rules and regulations for this, like, suppose there is 16, then you will not write 016, you will just write 16, if there is one, then 001. We are not doing this mathematics, you are understanding, so these are the notations, so usually we follow dotted decimal notation, which is

8:31 relatively easy to read, interpret, work with. Come on friends, now let's talk about the concept of classful address. See, anyway sir, we have understood that there is a 32-bit number and a 32-bit number is sufficient for any connection. I will explain it with unique identification on the internet. Suppose you have a mobile phone, usually it is a 10-bit number, a 10-digit number and within India we communicate anywhere but when there is an international call, what will you put first? First we put the country code, by which we identify to which country in the world the call is going and after that we put that 10-bit number, by which we can do unique identification within the country. This is

9:20 like the biggest network where there are many networks. So first of all listen to this thing carefully. It is a very interesting thing. We divide our 32-bit address into two parts. One is called prefix and the other is called suffix. Now why are we saying prefix, sir? Normally it is an English story. What is written first is called prefix. What is written later is called suffix. What is prefix? We call prefix as network ID. What is network ID? We call suffix as host ID. So what does this mean? We say what will be the value of n out of 32 bits? I will discuss that further. The first bits, the starting bits will tell me which network I have to go to, right? Because we have divided the internet into many small networks, all of which are interconnected, so the starting bits will tell me which

10:05 network I have to go to. After that, the remaining n is now gone. How much is left out of 32? 32 - n. So the remaining 32 - n bits will tell which computer has to be reached through which connection within that network. So this is the story. Whenever someone talks to you about Net ID, Host ID, Net ID, Host ID. Don't panic. Net ID, which network, Host ID, which computer within that network. Now what is a classful address sing. Look, the creator of the internet obviously felt that if the internet grows, there will be many networks in it. There will be large networks that will be connected to each other. Now what is one way? What should be the size of these networks and how many should they be? Let it be. That thing is left independent and people manage according to their own convenience. Whoever

10:51 needs a big network makes it bigger. Whoever needs a small network makes it smaller. But to make it, Although their estimation was wrong, what was done at that time, they thought according to their own understanding that how many big networks will be needed by the people, they standardized the process and what will be their size and that is what is called classful addressing idea. Let me explain to you, like suppose we are going to create a country, then we will think how many states should be there in it, how big should a state be, how many districts will be there in it or if we think in terms of networks, then we think in terms of cities, some cities are very big, metropolitan cities, their requirements are different, more people live in them, some cities are small, they will need different types of networks, similarly what did they do, they basically

11:37 created three types of networks, one we call class A people, which are very large networks and they are very less in number, second are class B people, which are relatively somewhere in the middle and third are class C people, which are very small networks but are very high in counting, so they worked according to their own understanding, which we call classful addressing. If I tell you once according to the exact value, then how the story goes, although in the next video I am going to talk about class A B C in detail, so see what did I do here, it is a 32-bit address, sir, the first bit was reserved for zero, so if your first bit is zero, it means you are a class A address and here it was also fixed what would be the length of the net ID, what would be the length of the host ID, so I

12:22 said in class A, as I told what does the net ID tell which network, what does the host ID tell which computer inside that network, so in a 30-bit address, in class A, I said that the net ID would be of 8 bits, the host ID would be of 24 bits in that too because distinction had to be made from the rest, if the first bit is zero, then I said this is a class A address, so you understand that I have 10 bits left, so 2 to the power of 7, that is, about 128 networks, which is relatively very less in number, but 2 to the power of 24, which is a very big number in itself, is about 160 crores. No sorry 1 crore 60 lakhs is going to be a very big number so they made an estimate that later on in the world we will make about 127 128 networks in which

13:08 each one is going to have more than 1 crore systems overall now obviously I do n't know how many companies will be there which will have such networks or countries which will need such networks or not but at that time they did it according to their own calculation if we see in dotted decimal notation then this range because the first bit is zero I am only talking about the prefix of the net ID so it is visible from 1 to 127 so after practicing it two-four times you should remember what did you do in the second case, made it equal now gradually because we are making the network smaller the network will become smaller so this host ID will keep getting smaller because the host ID tells how many people will be inside it so now made it equal prefix is ​​equal to suffix i.e. net ID is equal to host ID and here what did you fix because zero was already fixed

13:55 So the rest of the numbers got only one, that means the space on 50 went only to class A. Now the remaining was to be distributed among the big networks. The first bit was made one and the next bit was made black. If you don't understand in binary, then understand it in numbers. I have total numbers from 0 to 255, exactly half 0 to 127 with class A, then half of that, that is the next 64, 128 to 191 with B, then half of that 192 to 223 and then B and E got equal numbers of 161, so 224 to 239, 240 to 255 and accordingly you can see it in bits, the first bit is zero, the first bit is two bits 10, then 110, then 111 and then 111. Similarly,

14:41 when we went to c, now see what happened in s, three bits were reserved in s but the prefix was made bigger, the net ID and the suffix were very small, so 24 10 bits is the net ID or prefix and 8 bits is the suffix, that is, the host ID. So obviously here the number of networks, even if I remove the reserved 3 bits, how much is left from 24? 21 2nd to the power of 20 is approximately 10 lakhs, 1 million and multiply it by 2 as well, that means around 20 lakhs. There will be such small networks and in every network 2nd to the power of 8, that is, approximately 256 is going to come. I am going to talk about this in detail in the next video. So according to this, when they divided and assigned classes and gave ranges to each one, D is basically used for multicasting and E is reserved

15:27 for future purposes, which I will talk about in detail in the next video, but this was my understanding, I just want to explain to you what is classful addressing, so when the makers decided according to their own understanding that this will be done, it was called classful addressing, although with time we realized that The approximations were wrong and there were very different requirements, so this class full dressing is already an outdated fashion and nowadays we all do netting, super netting and class less inter domain routing which is all together a different story. Now that you have come this far, please like this video and give us a little motivation and in the next video, there will be all these classes, how many stations, how many networks will be there in each class, how much will be the count in it, these are very popular questions, they are asked again and again, I will talk about all of them, whatever

16:13 feedback you have, please do tell me by writing a comment, thank you so much, may God keep you all happy