The Three RFC 1918 Private Ranges
RFC 1918 (published 1996) reserves three IPv4 address blocks for private network use. Traffic from these addresses is dropped by internet routers and never routed publicly.
| Range | CIDR | Addresses | Class origin |
|---|---|---|---|
| 10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 | 16,777,216 | Class A |
| 172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 | 1,048,576 | Class B |
| 192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 | 65,536 | Class C |
10.0.0.0/8 — The Class A Private Range
This single /8 block contains over 16 million addresses, making it ideal for large enterprise networks, data centres, and cloud VPCs where large flat address spaces are needed.
- Range: 10.0.0.0 – 10.255.255.255
- Usable hosts: 16,777,214
- Common use: Enterprise LANs, data centres, Kubernetes pod networks, VPN allocations
- Typical subnetting: 10.0.0.0/8 is divided into /16 or /24 blocks per region/department
AWS uses 10.0.0.0/8 as the basis for many VPC configurations. Kubernetes typically uses 10.244.0.0/16 or 10.96.0.0/12 for pod and service networks.
172.16.0.0/12 — The Class B Private Range
This /12 block spans from 172.16.0.0 to 172.31.255.255 — 16 consecutive /16 networks.
- Range: 172.16.0.0 – 172.31.255.255
- Usable hosts: 1,048,574
- Common use: Medium-sized enterprise networks, Docker's default bridge network
- Note: Docker's default bridge uses
172.17.0.0/16
This range is often overlooked and is a good alternative when 10.x.x.x conflicts with VPN or cloud networks.
192.168.0.0/16 — The Class C Private Range
The most familiar private range — used by virtually every home router in the world.
- Range: 192.168.0.0 – 192.168.255.255
- Usable hosts: 65,534 (in the /16 block)
- Common use: Home networks (192.168.0.0/24 or 192.168.1.0/24), small offices
- Typical router default: 192.168.1.1 gateway, 192.168.1.0/24 LAN
Other Special IPv4 Ranges
| Range | Purpose | RFC |
|---|---|---|
| 127.0.0.0/8 | Loopback (localhost) | RFC 1122 |
| 169.254.0.0/16 | Link-local / APIPA | RFC 3927 |
| 0.0.0.0/8 | This network (unspecified) | RFC 1122 |
| 100.64.0.0/10 | Shared Address Space (ISP CGN) | RFC 6598 |
| 192.0.2.0/24 | Documentation / TEST-NET-1 | RFC 5737 |
| 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 | RFC 5771 |
| 240.0.0.0/4 | Reserved (IETF) | RFC 1112 |
| 255.255.255.255/32 | Limited broadcast | RFC 919 |
Which Private Range to Use?
- Small home or office network:
192.168.1.0/24— simple, familiar, plenty of room for typical use - Medium business:
172.16.0.0/12— large enough for segmentation, avoids VPN conflicts with 10.x - Enterprise / cloud / data centre:
10.0.0.0/8— maximum flexibility for complex subnetting and future growth - Avoid overlap with VPNs: If you connect to a corporate VPN, check which range it uses and choose a different one for your local network to prevent routing conflicts.