Working with IPv4 addressing

- The first topic we want to discuss in this course is the IP address. Specifically, we want to talk about the IPv4 address. The IPv4 address looks like this. An example'd be 192.130.241.27. An IP address identifies a computer's network and host ID. An IP address is a 32-bit long, binary address. An IPv4 address is broken down into four 8-bit groups.

Each one of those 8-bit groups is written as a decimal number from 0 to 255. IPv4 addresses also come with subnets. Example of a subnet would be something like 255.255.255.0. Each IP address has a subnet that goes with it. All IP addresses must have a matching subnet for it to work in a computer. The purpose of the subnet is to divide the IP address into its network and host portions.

The way that the subnet mask separates the network from the host portion, is by converting the IP address, such as 172.130.241.26, into its binary equivalent. It then takes the subnet mask, which in this case is 255.255.255.0, and converts that to a binary equivalent as well. Once the computer has the binary equivalent of the IP address, and the subnet mask, it then compares the IP address to the subnet mask.

Everywhere the computer sees two 1s, it places a 1, and everywhere the computer sees another combination, such as the 0 1, or 1 0, or even two 0s, it places a 0. Once the computer gets done comparing the IP address to the subnet mask, it goes and matches the result to the original IP address. The portion of the result that is the same up to the last 1, is determined to be the network portion of the address, and the remainder of the IP address is determined to be the host portion of the address.