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IP addressing refers to assigning a 32-bit binary numerical label to all the devices connected to a network that communicates to the internet. The 32-bit IPv4 address is subdivided into 4 x 8-bit segments, which are known as octets.
As only a few users work with 32-bit IPv4 addresses, the IP address is generally expressed in the dotted-decimal format. Here, each octet is assigned to an equivalent decimal number and the four decimal values are separated using periods. Typically, the eight binary bits can represent any number from 0 to 255. This means that each of the parts of the dotted-decimal in an IPv4 address can be any decimal from 0 to 255.
Although IP addresses are broken into four parts using periods, the first two segments combine to denote the network ID, while the last two represent the host ID. However, not all IPv4 addresses have the same format. For instance, sometimes, only the first one could be the network ID while the other three will be the host ID or vice versa. In a network that has multiple devices connected, the network ID in the IP address will be the same while the host ID will change from device to device.
The segments in the IPv4 address vary as per the address Class allotted to the network. Class A IPv4 addresses will have the first 8 bits reserved for the network ID while the rest 24 bits will denote the host ID. Class B IPv4 addresses will use the first 16 bits to represent the network ID and the last 16 bits for the host ID. The first 24 bits of Class C IPv4 addresses, on the other hand, will denote the network ID while the remaining 8 bits represent the host ID.
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IPv4 Addresses Tips[/caption]
To assign an IP address, the Class A format supports up to around 224 hosts. On the contrary, a Class C network can support only up to around 28 hosts. Yet again, many more combinations of network IDs can be used in the Class C format to support more hosts. Generally, if the 32-bit binary address begins with a 0, then it is in the Class A format, while the ones starting with 10 are Class B addresses. Class C format will have the first 32-bit binary address starting with 110.
Theoretically, the internet can accommodate only 127 Class A networks. However, each of the networks can have up to 17 million hosts. Class B networks, although not as large as Class A networks, can have about 65,000 hosts per network. Class C networks are a lot smaller and can support up to 254 hosts only, which is why there are more than 2 million Class C networks on the internet.