Basics of IP Addressing

Hello everyone, today we will see the basics of IP addressing. Now, we will see the outcomes of this session. Upon the completion of this session, the learner will be able to understand the basics of IP addressing, we will also come to know how to see the IP address in real device, And we will also identify valid and invalid IP addresses. Now, we will move on to the definition of an IP address. IP address: IP stands for Internet Protocol. IP is an important part in the internet. And every node in the computer network is identified with the help of IP address only. We will see an example first and then we will come to the definition again. This example involves lot of end devices and lot of intermediary devices. Now, there is a computer and this computer wants to send some data to this computer. It means the computer with IP address 172.15.150.2 is going to send some data to 192.168.150.2. So, this is what we call as an IP address because every node in the computer network is identified with the help of IP address only. Now, we will see more about IP address. When I say IP address, there are two variations: IPV4 address and IPV6 address. In this computer network series, we will be learning about both IPV4 and IPV6 elaborately in the upcoming lectures. For time being, now we will focus on IPV4 address. We already know every node in the computer network is identified with the help of IP address only. And they are logical address too. Let me explain what is a logical address. If you take this scenario, this is a local area network, which is in New Delhi. And this is another local area network, this is in Chennai. Suppose, if I take this computer and if I place this computer in the local area network of Chennai, and I want this newcomer to participate in the local area network which is in Chennai, I can simply remove this IP address and I can assign an IP address in this range. For example, this computer is assigned with 192.168.150.2 and this is with 150.3 and this is with 150.4. So what I can give-- I can take this computer and I can place it here and I can assign it as 192.168.150.5. And thereby we can make this newcomer to participate in the local area network. Since these IP addresses can be changed, based on the logic or the location we call IP addresses as logical address. And that is what I have mentioned here. So, IP addresses are logical addresses. Because we can change the IP address based on the location of the device. And we can assign this IP address manually or even dynamically. We will talk about this point in the network layer part. Time being, you just understand that IP addresses can be assigned manually or even dynamically. And IPV4 addresses are represented in decimal and it has four octets. It mean four parts. Say x.x.x.x and each of this x takes a value between 0 and 255. So this x can be between 0 and 255, likewise all the x can be between 0 and 255. So, the starting IP address will be 0.0.0.0 to 255.255.255.255. And the total number of bits in every IP address will be 32 bits. We will now see how to see, an IP address in real device. To view the IP address in real device, click the start menu type "cmd" and give enter. When you type "cmd" and press enter, you will be given up with the command prompt. This is the command prompt of the windows operating system that I am using. And it can execute all the commands whatever I give. Here, I am intended to find the IP address of this computer. To know the IP address of this computer, I have to give the command ipconfig. When I give "ipconfig" in the command prompt, it gives the IP address of this computer. If you observe, I am not using ethernet based local area network. Because I have connected my computer using Wi-Fi. And that is why, it is showing wireless LAN with certain properties. If you observe here, IPV4 address is shown. This is the IP address of this computer and any data goes form this computer uses this as the IP address for identification purpose. So, the IP address for this computer is 192.168.29.173. So far we have seen how to see IP address in real device. There is an interesting activity for you. We are required to identify the valid and invalid IP addresses in the following set. So set of IP addresses are given, and we are required to identify valid and invalid IP addresses and place the options in the appropriate columns. And there are two columns given. One is the column for valid IP addresses and another one is for invalid IP addresses. Suppose, if you find 'a' is a valid IP address, mark it as a here. And if you find b is an invalid IP address, mark it b here. And you should know why they are valid and why they are invalid. Please pause this video for a while and make a note of the answers against the columns. If you are done, compare your answer with the answer that I am depicting. So the valid IP addresses are a,c and d and the invalid IP addresses are b, e and f. Now, we will see why they are valid and why these are invalid. a is a valid IP address because it should have four octets and of course this is having four octets. One, two, three and four and each octet is between 0 and 255. Yes, a is a valid IP address. And b is not a valid IP address. Though it has four octets, one, two, three and four, fourth octet is invalid because any octet should be between 0 and 255. So, 256 is not a valid entry. So b is invalid. Coming to c, it is a valid IP address, because each octet can be between 0 and 255. So c is valid. And d is also valid. Why because, d is also the last IP address of the IPV4 IP address set. And each octet is between 0 and 255, so, d is valid IP address. If you observe e, e is an invalid IP address. Because it has one, two, three, four and five octets, at the same time, if you observe this octet, this is greater than 255. So e is invalid for two reasons- number 1: It has five octets and number 2: The range in the octet in not appropriate. So, it should be 0 and 255, but we can see there are 345 and 456 and these values are not between 0 and 255. Coming to the option f, this is an invalid IP address. Why because, there is an octet with 2e. We know very well that IPV4 addresses must be in decimal. Even if e is an hexadecimal character but that is not valid here. Because any IP address in IPV4, it should be in decimal only. So f is also not valid. I hope the session will be helpful to understand what are valid IP addresses and what are invalid IP addresses. That's it guys. I hope now understood the basics of IP addressing, you will also know how to see IP address in real device, and we will be able to identify valid and invalid IP addresses.