IANA Reserved IPv4 Address Ranges
Complete reference of IANA reserved IPv4 ranges including RFC 1918 private, RFC 5737 documentation, RFC 6598 CGNAT, and other special-purpose address blocks.
Detailed Explanation
IANA Reserved IPv4 Address Ranges
The Internet Assigned Numbers Authority (IANA) reserves several IPv4 address ranges for special purposes. These addresses cannot be used for regular public-facing hosts.
Complete Reserved Range Table
| Range | Purpose | RFC |
|---|---|---|
| 0.0.0.0/8 | "This" network | RFC 791 |
| 10.0.0.0/8 | Private (Class A) | RFC 1918 |
| 100.64.0.0/10 | Shared / CGNAT | RFC 6598 |
| 127.0.0.0/8 | Loopback | RFC 1122 |
| 169.254.0.0/16 | Link-Local (APIPA) | RFC 3927 |
| 172.16.0.0/12 | Private (Class B) | RFC 1918 |
| 192.0.0.0/24 | IETF Protocol Assignments | RFC 6890 |
| 192.0.2.0/24 | Documentation (TEST-NET-1) | RFC 5737 |
| 192.88.99.0/24 | 6to4 Relay Anycast | RFC 3068 |
| 192.168.0.0/16 | Private (Class C) | RFC 1918 |
| 198.18.0.0/15 | Benchmarking | RFC 2544 |
| 198.51.100.0/24 | Documentation (TEST-NET-2) | RFC 5737 |
| 203.0.113.0/24 | Documentation (TEST-NET-3) | RFC 5737 |
| 224.0.0.0/4 | Multicast (Class D) | RFC 5771 |
| 240.0.0.0/4 | Reserved (Class E) | RFC 1112 |
| 255.255.255.255/32 | Limited Broadcast | RFC 919 |
Documentation Ranges
When writing examples, tutorials, or documentation, use these ranges instead of real addresses:
- 192.0.2.0/24 (TEST-NET-1)
- 198.51.100.0/24 (TEST-NET-2)
- 203.0.113.0/24 (TEST-NET-3)
CGNAT: 100.64.0.0/10
Carrier-Grade NAT uses 100.64.0.0 – 100.127.255.255 as a shared address space between ISPs and their subscribers. If your device shows a 100.64.x.x address, you are behind carrier-grade NAT.
Class E: 240.0.0.0/4
The 240-255 range was reserved for "future use" but that future never arrived. Despite proposals to reallocate it, widespread OS and router support issues make these addresses effectively unusable.
Use Case
A technical writer creating API documentation uses 198.51.100.0/24 (TEST-NET-2) for example IP addresses instead of real IPs, following the RFC 5737 recommendation for documentation.