Every router and computer on the network has to have an IP Address.
The best way to understand how IP Addresses work is to think about how the postal service works. Every house has a unique address, a street name and a house number. There can be multiple house numbers on one street, and there can be houses with the same number as long as they are on different streets. Just like a house address as two different parts an IP Address also has two different parts to it, a network part and a host part.
An IP Address is 32 bits long. In order to make it easier for us humans to read what the IP Address is, it is in the format of dotted decimal. There are 8 bits for each 4 sections (8*4=32). An example of an IP Address is 192.168.1.1 or in binary 11000000.10101000.00000001.00000001.
With every IP Address there is always a subnet address or subnet mask to determine which part of the IP Address is the network and which part is the host. For example the subnet mast for the above ip address (191.168.1.1) could be 255.255.255.0. Without going into the details yet, the network part of the address (or the street name) is the first 3 octets of the IP Address: 192.168.1 and the host potion is the last octet: 1. The above subnet mask in binary is 1111111.111111.11111111.00000000. The one’s determine the network part and the zero’s determine the host part. In a subnet mask the ones are always at the beginning and never will have zero’s in between them.
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