Reserved IP Address Ranges — Complete Guide
Every reserved IPv4 range: loopback (127/8), link-local (169.254/16), CGNAT (100.64/10), documentation ranges, multicast — and what each is used for.
Complete reserved range table
| Range | Name | RFC | Purpose | Routable? |
|---|---|---|---|---|
| 0.0.0.0/8 | This network | RFC 1122 | Source-only: host on this network | No |
| 10.0.0.0/8 | Private Class A | RFC 1918 | Private use (LAN, VPC, enterprise) | No |
| 100.64.0.0/10 | CGNAT Shared Space | RFC 6598 | Carrier-Grade NAT between ISP and subscribers | No |
| 127.0.0.0/8 | Loopback | RFC 5735 | Localhost / loopback — stays on host | No |
| 169.254.0.0/16 | Link-Local (APIPA) | RFC 3927 | Auto-assigned when DHCP fails; IMDS endpoint | No |
| 172.16.0.0/12 | Private Class B | RFC 1918 | Private use (LAN, VPC) | No |
| 192.0.0.0/24 | IETF Protocol Assignments | RFC 5736 | Reserved for IETF protocol use | No |
| 192.0.2.0/24 | TEST-NET-1 | RFC 5737 | Documentation and example use only | No |
| 192.88.99.0/24 | 6to4 Relay Anycast | RFC 3068 | Deprecated IPv6-to-IPv4 transition | No |
| 192.168.0.0/16 | Private Class C | RFC 1918 | Private use (home, SOHO, LAN) | No |
| 198.18.0.0/15 | Benchmarking | RFC 2544 | Network benchmarking / performance testing | No |
| 198.51.100.0/24 | TEST-NET-2 | RFC 5737 | Documentation and example use only | No |
| 203.0.113.0/24 | TEST-NET-3 | RFC 5737 | Documentation and example use only | No |
| 224.0.0.0/4 | Multicast | RFC 5771 | IP multicast groups (OSPF, mDNS, IGMP) | Yes |
| 240.0.0.0/4 | Reserved (Class E) | RFC 1112 | Reserved for future use / experimental | No |
| 255.255.255.255/32 | Limited Broadcast | RFC 919 | Broadcast to all hosts on local segment | No |
169.254.169.254 — The cloud metadata IP
The link-local address 169.254.169.254
is used by AWS, Azure, and GCP as the Instance Metadata Service (IMDS) endpoint.
From any EC2 instance, you can run:
This IP is not routable — it only works from within the instance on the link-local interface. AWS IMDSv2 requires a session token first (PUT request) for improved security.
Frequently Asked Questions
Which IP ranges are reserved and cannot be used publicly?
The major reserved ranges are: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 (RFC 1918 private); 127.0.0.0/8 (loopback); 169.254.0.0/16 (link-local); 100.64.0.0/10 (CGNAT); 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24 (documentation only); 224.0.0.0/4 (multicast); and 240.0.0.0/4 (reserved). None are routable on the public internet.
What is 100.64.0.0/10 used for?
100.64.0.0/10 is the Shared Address Space (RFC 6598) used for Carrier-Grade NAT (CGNAT). ISPs use it between their NAT infrastructure and subscribers when public IPs are scarce. It behaves like a private range but is distinct from RFC 1918 — you may encounter it as an IP address on mobile networks.
Can I use documentation ranges like 192.0.2.0/24 in production?
No. TEST-NET ranges (192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24) are reserved by RFC 5737 for documentation and examples only. Assigning them to real devices will cause routing failures — these addresses may be dropped or misrouted by internet infrastructure.