Computer networks use IP addresses as identification numbers. There are millions of IP addresses. Network addresses organize IP addresses into groups. Broadcast addresses represent all addresses of groups.
IP addresses
An IP address is a unique identification number. Each device on an IP network needs an IP address. Devices use IP addresses to identify each other. They can have multiple IP addresses. An IP address is 32 bits in length. The 32 bits make a total of 4,294,967,296 IP addresses. Finding an IP address from addresses is the most challenging task. To make this task easy, IP address designers developed many methods. IP classes and network addresses are two methods of them.
IP classes
There are five IP classes. These classes are A, B, C, D, and F. Each IP address belongs to one of these classes. The first number of the IP address shows its class.
The following table lists IP classes.
| Class | First number range | Start address | End address |
| A | 0 - 127 | 0.0.0.0 | 127.255.255.255 |
| B | 127 - 191 | 127.0.0.0 | 191.255.255.255 |
| C | 192 - 223 | 192.0.0.0 | 223.255.255.255 |
| D | 224 - 239 | 224.0.0.0 | 239.255.255.255 |
| E | 240 - 255 | 240.0.0.0 | 255.255.255.255 |
Network addresses
An IP address consists of two types of addresses: network address and host address. Network addresses combine multiple IP addresses in a group known as an IP subnet. Host addresses provide a unique identity to each IP address in the group. A network address is the group address. All group members use the same network address. A host address is a unique address in the group.
An IP address is always used with the subnet mask. A subnet mask separates the network address from the host address in the IP address.
A subnet mask is also 32 bits in length. It uses the same notation the IP address uses.
It assigns an individual bit for each bit of the IP address. If an IP bit belongs to the network portion, the subnet mask turns on the related bit in the subnet mask. If an IP bit belongs to the host portion, the subnet mask will turn off the related bit in the subnet mask.
Broadcast address
Each IP subnet consists of three types of IP addresses: IP addresses, a network address, and a broadcast address. The network address is the first address of the IP subnet. The broadcast address is the last address of the IP subnet. All addresses between the network address and the broadcast address are IP addresses.
A network address provides identity to the IP subnet. Routers use network addresses to find IP subnets and make forwarding decisions.
An IP address provides a unique identity to a device in the IP subnet. An IP address belongs to a single device in the IP subnet.
A broadcast address belongs to all devices in the IP subnet. Any message sent to this address reaches all devices on the subnet. A broadcast is a destination-only address. It is never used in the source address field of data packets.
