A method of dividing IPv4 addresses into classes.
Commonly used as a suffix after a network address like /24 in 192.168.10.4/24
Indicates the # of bits used for the network range.
Overview
| Class | Host identifier size (bits) | Address range |
|---|---|---|
| A | 24 | 0.0.0.0–125.255.255.255 |
| Loopback | - | 126.0.0.0-12 |
| B | 16 | 128.0.0.0–191.255.255.255 |
| C | 8 | 192.0.0.0–223.255.255.255 |
| D(multicast) | – | 224.0.0.0–239.255.255.255 |
| E(reserved) | - | 240.0.0.0-255.255.255.255 |
Classes
https://www.meridianoutpost.com/resources/articles/IP-classes.php
Class A
- Subnet Mask
255.0.0.0 - Network ID first octet
- Host ID last 3 octets
- Public IP range
0.0.0.0 - 127.255.255.255 - Private IP range
10.0.0.0 - 10.255.255.255or10.*.*.*
Class B
- Subnet Mask
255.255.0.0 - Network ID first 2 octets
- Host ID last 2 octets
- Public IP range
128.0.0.0 - 191.255.0.0 - Private IP range
172.16.0.0 - 172.31.255.255or172.16-31.*.*
Class C
- Subnet Mask
255.255.255.0 - Network ID first 3 octets
- Host ID last octet
- Public IP range
192.0.0.0 - 223.255.255.0 - Private IP range
192.168.0.0-192.168.255.255or192.168.*.* - Special Loopback IP range
127.0.0.0 - 127.255.255.255or127.*.*.*