IPv4 Address Classes
IPv4 Address Classes
- There are 5 IPv4 Address Classes defined by RFC 1918, each allocated to a specific purpose or consumer.
- NOTE: While occasionally referenced in the CCNA, they are not relevant when it comes to subnetting
| Class | Purpose | First Octet | First Octet Range | Slash Subnet | Dotted Subnet | Private IP Range | Private IP Subnet Mask |
|---|---|---|---|---|---|---|---|
| A - "This Network" | RFC Reserved - "This Network" | 0.0.0.0 | - | /8 | 255.0.0.0 | 0.0.0.0 - 0.255.255.255 | --- |
| A | Large networks | 1-126 | 128 | /8 | 255.0.0.0 | 10.0.0.0 - 10.255.255.255 | /8 |
| A - Loopback | RFC Reserved - Loopback | 127 | - | /8 | 255.0.0.0 | 127.0.0.0 - 127.255.255.255 | --- |
| B | Medium/Large networks | 128-191 | 64 | /16 | 255.255.0.0 | 172.16.0.0 - 172.31.255.255 | /12 |
| C | Small Networks | 192-223 | 32 | /24 | 255.255.255.0 | 192.168.0.0 - 192.168.255.255 | /16 |
| D | Multicast addresses | 224-239 | 16 | --- | --- | --- | --- |
| E | Experimental | 240-255 | 16 | --- | --- | --- | --- |
Private IPv4 Address Ranges
| Class | Purpose | Private Network Address | Slash Subnet | Dotted Subnet | Private IP Range |
|---|---|---|---|---|---|
| A | Large networks | 10.0.0.0 | /8 | 255.0.0.0 | 10.0.0.0 - 10.255.255.255 |
| B | Medium/Large networks | 172.16.0.0 | /12 | 255.240.0.0 | 172.16.0.0 - 172.31.255.255 |
| C | Small Networks | 192.168.0.0 | /16 | 255.255.0.0 | 192.168.0.0 - 192.168.255.255 |