| Address Class | Purpose | Beginning Address | Ending Address | Network Octets | Address Mask |
| A | Large Networks | 1.1.1.1 | 126.255.255.255 | 1 | 255.0.0.0 |
| B | Medium Networks | 128.0.0.1 | 191.255.255.255 | 2 | 255.255.0.0 |
| C | Small Networks | 192.0.0.1 | 223.255.255.255 | 3 | 255.255.255.0 |
| D | Multicast | 224.0.0.1 | 239.255.255.255 | N/A | N/A |
| E | Experimental | 240.0.0.1 | 255.255.255.255 | N/A | N/A |
| EXCEPTIONS: | |||||
| PRIVATE | Pvt LANS | 10.0.0.0 | 10.255.255.255 | Variable | Variable |
| LOOP | Testing (Loopback) | 127.0.0.0 | 127.255.255.255 | N/A | N/A |
| PRIVATE | Pvt LANS | 172.16.0.0 | 172.31.255.255 | Variable | Variable |
| PRIVATE | Pvt LANS | 192.168.0.0 | 192.168.255.255 | Variable | Variable |
| Additional Restrictions: | |||||
| 1) The client octets may not contain all 0's (Reserved for intra-network router broadcasts) | |||||
| 2) The final octet may not contain 255 (Reserved for network broadcasts) | |||||