Today we are going to talk about IPv4 which stands for internet protocol version 4. An IP is a logical address that is used in layer 3 to identify host addresses, default gateways, loopback interfaces, and router interfaces. An IP address is much like a home address, where it represents where to send something to for a specific person (for address) or host (for host). A host can be anything where traffic can be sent such as a PC, IoT devices, smartphones, servers or printers.
Before you can understand what IPv4 is, it is crucial that you understand what binary is. This is an important thing to understand if you ever want to understand networking. Unlike humans who speak and listen in human languages (English), unfortunately computers do not talk in human languages. A computer can only interpret either 1 or 0, 1 for being “on” or “high voltage” or 0 for being “off” or “low voltage.” For copper cables, binary speaks with high voltage or low voltage. In fiber optic cables, the binary speaks on or off meaning if light is passing the binary is 1 and if no light is passing the binary is 0. Computers rely on electrical circuits or transistors that will only read 1s and 0s one bit at a time. Since this is the case, data (text, images, IP addresses) are converted to binary before it is transmitted in order to be interpreted properly. Binary consists of bytes and bits. A bit is the smallest form of binary data, look at this “1”. This is a bit that means on. And “0”, this is a bit that means off. These bits are grouped together for communication and they are called bytes. A byte is 8 bits back to back, it will look like this 01011100.
Now that we know what binary is, what does it have to do with an IPv4 address? Well IPv4 is written in DDN which stands for dotted decimal notation. This means that binary has been converted from 32 contiguous bits into something that is readable and easy to understand by the human eye. When a packet is traversing the network the source IP will look something like this to the computer (11000000101010000000000100000000).
As you can see, that would be brutal for a network engineer to configure an ip address. What an IPv4 does is that it turns those 32 bits into 4 groups of 1 byte or 8 bits, each group separated by a decimal. The end result looks something like this 192.168.1.1. As you can see that it is more appealing to the human eye, and much easier to scale this way. Essentially it turns that long 32 bits into this 11000000.10101000.00000001.00000000 into this 192.168.1.1. Each group is called an “octet” and the decimal value can range from 0 to 255. IP addresses are crucial for internetworking communication and are vital for packets arriving at the correct destination host.
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