Private IP Ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16

RFC 1918 Private IP Ranges

RFC 1918 defines three IPv4 address blocks reserved for private (non-routable) use. These addresses are used inside organizations and are never routed on the public internet. Routers automatically drop packets with RFC 1918 source or destination addresses at network boundaries.

The Three Private Ranges

Range	CIDR	Mask	Total Addresses
10.0.0.0/8	10.0.0.0/8	255.0.0.0	16,777,216
172.16.0.0/12	172.16.0.0/12	255.240.0.0	1,048,576
192.168.0.0/16	192.168.0.0/16	255.255.0.0	65,536

10.0.0.0/8 — The Largest Block

The 10.0.0.0/8 range provides over 16 million addresses (10.0.0.0 to 10.255.255.255). It is the preferred choice for large enterprises and cloud providers. AWS, Azure, and GCP all commonly use this range for VPC configurations. Organizations subdivide it hierarchically — for example, 10.[region].[site].[host].

172.16.0.0/12 — The Mid-Sized Block

The 172.16.0.0/12 range spans 172.16.0.0 to 172.31.255.255 (note: /12, not /16). It provides over 1 million addresses across 16 contiguous /16 blocks. Docker uses 172.17.0.0/16 by default, and Kubernetes clusters often allocate pod networking from this range. It is popular for VPN networks to avoid conflicts with common 192.168.x.x home networks.

192.168.0.0/16 — The Home Network Block

The 192.168.0.0/16 range (192.168.0.0 to 192.168.255.255) is the most recognized private range. Nearly every home router defaults to a 192.168.x.x/24 subnet. With only 65,536 addresses, it is too small for large enterprises but perfect for homes and small offices.

Which Range Should You Use?

• Home/small office: 192.168.0.0/16 (typically a single /24)
• Medium organizations: 172.16.0.0/12 for over a million addresses
• Large enterprises and cloud: 10.0.0.0/8 for maximum address space

NAT and Private Addresses

NAT (Network Address Translation) allows devices with private addresses to access the public internet. The router translates private source IPs to its public IP for outbound traffic and reverses the translation for responses.

Avoiding Conflicts

When merging networks or establishing VPN connections, overlapping private ranges cause routing failures. Plan your addressing scheme carefully and avoid common defaults like 192.168.1.0/24 or 10.0.0.0/24.