Reserved IPv4 Ranges
Private Address Space (RFC 1918) — Used within home, office, and enterprise networks for internal communication.
| Range | CIDR | Use |
|---|
| 10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 | Large corporate/private networks |
| 172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 | Medium-sized networks |
| 192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 | Small/home office networks |
Carrier-Grade NAT (CGNAT) (RFC 6598) — 100.64.0.0/10 (100.64.0.0 – 100.127.255.255) designed for service provider internal networks.
Link-Local (RFC 3927) — 169.254.0.0/16 (169.254.0.0 – 169.254.255.255) used for APIPA when a device cannot reach a DHCP server.
Loopback (RFC 1122) — 127.0.0.0/8 (127.0.0.1 – 127.255.255.255) used for testing network applications on the local machine.
Documentation (RFC 5737) — Used for examples in documentation and tutorials.
| CIDR | Name |
|---|
| 192.0.2.0/24 | TEST-NET-1 |
| 198.51.100.0/24 | TEST-NET-2 |
| 203.0.113.0/24 | TEST-NET-3 |
Experimental / Reserved (RFC 1112) — 240.0.0.0/4 (240.0.0.0 – 255.255.255.254) reserved for future use or experimental purposes.
Broadcast — 255.255.255.255/32 sends packets to all hosts on a local network segment.
These addresses are typically blocked by ISPs and routers to prevent traffic from leaking into the public internet. ARIN and regional internet registries (RIRs) govern the allocation of public address space.