Representation
An IPv4 address is a 32-bit number, typically represented in dotted decimal format. This format consists of four decimal numbers separated by dots, where each number ranges from 0 to 255. For example:
192.168.1.1
Each decimal number represents 8 bits (one byte), so the entire IPv4 address is composed of 4 bytes.
IP Address Classes
IPv4 addresses are divided into five classes: A, B, C, D, and E.
| class | Start address | End address | Default subnet mask |
|---|
| A | 1.0.0.0 | 127.255.255.255 | 255.0.0.0 |
|---|
| B | 128.0.0.0 | 191.255.255.255 | 255.255.0.0 |
|---|
| C | 192.0.0.0 | 223.255.255.255 | 255.255.255.0 |
|---|
| D | 224.0.0.0 | 239.255.255.255 | - |
|---|
| E | 240.0.0.0 | 255.255.255.255 | - |
|---|
Reserved IP Addresses
Certain IPv4 addresses are reserved for specific purposes and cannot be used as regular host addresses. These reserved addresses include:
| Reserved IP Addresses | Start address | End address | purposes |
|---|
| Private IP Addresses (Class A) | 10.0.0.0 | 10.255.255.255 | Used within local area networks (LANs) and not routable on the internet |
|---|
| Private IP Addresses (Class B) | 172.16.0.0 | 172.31.255.255 | Used within local area networks (LANs) and not routable on the internet |
|---|
| Private IP Addresses (Class C) | 192.168.0.0 | 192.168.255.255 | Used within local area networks (LANs) and not routable on the internet |
|---|
| Loopback Addresses | 127.0.0.0 | 127.255.255.255 | Used for testing and communication within the local host, typically 127.0.0.1 |
|---|
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