Hello friends, welcome to Gate Smashers. The topic is Class D & Class E in IP addressing. This topic comes in Classful Addressing where we divide IP Addresses into 5 classes. Class A, B, C, D and E. We have already discussed about Class A, B and C. In this video we are going to talk about Class D and Class E. So talking about Class D first, the 32 bit IP Address here, I have made 4 octets. Octet means I have made 4 octets of 8 bits each. Now the first octet here, in that I have written 8 places, first I will find out range. Range means if you are given an IP Address, then by looking at that IP Address how can you know if it belongs to Class D or not. And anytime if you want to find out to which class any IP Address belongs, then you can find out only by the first octet. So we are only taking the value of first octet here. So first of all, the first 4 values in Class D is 1110. Means these 4 values are fixed. Means the values of these 4 places is fixed you cannot change it. Means you cannot change 1110. Means if you are given an IP Address in binary represenation then how can you know that the IP Address belongs to Class D? You see the first 4 bits and these are what? Prefixed. Prefixed means it's unique. You will not get any different IP Address if it is 1110, if first 4 bits are these then it is definitely part of Class D. So that's why we fixed the first 4 bits, we cannot change them. So means how many bits remaining I have? How many places remain? 4 places, 1, 2, 3, 4. In these 4 places how can I put values? Either I can put minimum what? 0000. Or 0001, 0010, this way what will be last value? 1111. Means all 4 1s is the maximum we can put here. Now don't forget the previous values that is 1110 because when you convert this into decimal, you have to do collectively means overall, the whole thing you have to convert. So this whole 111 followed by five 0s, if I convert it into decimal, then this value comes 224, means Class D starts from where? It starts from 224. And if I see last value, after that will come 225, 226, this last value in decimal conversion will be what? 239. I means to say that if you are given any IP Address and in its first octet value is between 224 to 239 then you can directly say that this belongs to Class D. So means how many values come here? These are 16 values means I have 16 values in this range. I am only talking in this range here. Now next point that comes here is like we discussed in Class A, Class B or Class C, how many IP Addresses are possible, here if we see, number of IP Addresses in Class D, how many number of IP Addresses are possible? So how will you find out? 4 bits are fixed here, we can't touch them. Remaining how many bits are there? 8 and 8, 16, and 8, 24, 25, 26, 27, 28. Means 2 raised to power 28. Because 28 bits are being used to represent IP Address because you can put anything in these values, 0 or 1, 0 or 1 combinations you can put. But these 4 values are fixed, so how many values remain? 28. So total number of IP Addresses are how many? 2 raised to power 28 in Class D. Which is nearabout 6.25% of the total IP Addresses. Whatever number of IP Addresses is there out of that this value is 6.25%. If we see this generally, it is nearabout 25 crore, approximate. Means this value is around 250 million, this value is around 250 million. The next point which we discussed in Class A, B, C number of networks and number of hosts. But here in Class D there is no network, there is no host because all these 2 raised to power 28 IP Addresses are reserved, means to any network, means if some organization says that it wants a Class D address, it won't get because this is reserved. Why? For multicasting or group broadcast or group emailing. Means if some groups are made, online like some research related group is made, then people in the group can use Class D, but it has a very big disadvantage, what is it? Nearabout 2 raised to power 28 which is nearabout 25 crores, so many IP Addresses are wasted here because groups are very less, so many groups have not been made in the world. And this concept of classes, because of this, because many IP Addresses are wasted, reserved, but users' demand is increasing. So that's why the concept of Classful Addressing degraded slowly. We'll talk about this later, first let's come to Class E. So there is no funda of network, no funda of host, because all these 2 raised to power 28 are reserved which is nearabout 250 million. Here we are talking about Class E. Talking about Class E, in Class E also we have the same 4 octets of 8 bits each but the first 4 positions here are 1111 means first 4 positions are fixed. You cannot touch them, so how many positions remain here? 8, 8, 8, 24 and 4, 28. Means here also I have total 2 raised to power 28 number of IP Addresses in CLass E which is nearabout 6.25% of the total IP Addresses because values of these 2 are same. Means here also around 250 million values, means 25 crore values are there, and here also around 250 million values, means 25 crore values are there. And problem is that the IP Addresses of Class E, 2 raised to power 28 which is a very huge number, they are all reserved for Military purposes. They are already reserved for Military purpose. So if I talk about range here, what you have to do for range is simple, the last ones... How you can find out that any IP Address belongs to Class E? You just come to the first octet, 4 values in first octet are already fixed, in these 4 values what change you can make? 0000, 0001, or value can be 1111. And there are four 1s at starting, don't forget these. So if you see this, this value in decimal becomes what? 240. And this value becomes 255. So means range is what? 240 to 255. Means if any IP Address starts in this range then you can find out that it belongs to Class E. In this also there is no funda of network, no number of hosts to find out because the IP Addresses 2 raised to power 28 all are reserved for Military purpose. Means in a way, kind of reservation means here is wastage because users are increasing day by day, and here already huge amount of IP Addresses are reserved. That's why the concept that came after 1993 of Classless Addressing which was widely used later. So that's why as many examples we did here, as many real life examples we did, those examples are alright, but these examples were used before 1993. When users' demand increased and when flexibility came, there I had to go to Classless. We will discuss about Classless later. So here if we see a simple example, if you are given an IP Address, let's say 239.1.2.3 So you can be asked this IP Address belongs to which class. So you can find out that this IP Address is of Class D, but how many networks, how many hosts you cannot find out. And similarly if you are given some IP Address 245.0.1.2, so if you are asked which class it belongs to, then you have to check range, 245 comes in this range, so this is Class E IP Address, so in this there is no concept of network and host because all these IP Addresses which is total of about 500 million. This value is around 500 million, and all these IP Addresses are reserved as it is. That's why... They reserved around 50 crore IP Addresses. So that's why this value matters a lot and they reserved these values. So this is all about the Class D and E. Thank you.