Private IP Ranges Explained

Quick answer: Private IP addresses are reserved for internal networks. They are not routed across the public internet, so homes, offices, and cloud networks can reuse the same address space independently.

The three IPv4 ranges come from RFC 1918. IPv6 has a comparable internal-use range called Unique Local Addresses (ULA), defined by RFC 4193.

The private ranges at a glance

10.0.0.0/8 (legacy Class A private range)

The largest private IPv4 block. It is common in large organisations, campus networks, and multi-site environments where many subnets are needed. Under the obsolete classful networking system, it corresponds to one private Class A network.

172.16.0.0/12 (legacy Class B private ranges)

This range covers 172.16.0.0 through 172.31.255.255 and is often used for VPN pools and cloud VPCs. Under the legacy classful system, it sits in Class B address space and spans 16 consecutive Class B networks from 172.16.0.0/16 through 172.31.0.0/16. It provides more than one million addresses, reducing the likelihood of conflicts with common home-network ranges such as 192.168.0.0/16. It is also often allocated as an isolated “island” separate from enterprise core networks that commonly use ranges such as 10.0.0.0/8, making it well suited to separating cloud resources and container networks such as Docker.

192.168.0.0/16 (legacy Class C private ranges)

The familiar choice for home routers and small office networks. Under the legacy classful system, it sits in Class C address space and spans 256 consecutive /24 Class C networks. A router will often assign addresses from 192.168.0.0/24 or 192.168.1.0/24 to devices on the local network.

fc00::/7

IPv6 Unique Local Addresses cover fc00::/7; in practice, locally assigned addresses normally begin with fd. Like private IPv4 ranges, they are intended for internal use and are not globally routed.

Why private addresses are useful

• They can be reused: Your 192.168.1.10 can exist in millions of unrelated networks without conflict.
• They reduce public IPv4 demand: NAT lets many internal devices share a smaller number of public addresses.
• They help separate internal services: Private addressing is useful for printers, databases, internal dashboards, and service-to-service traffic.

Private does not mean secure by itself. A private address should still be protected with sensible access controls, network segmentation, and authentication. Learn more about NAT and the difference between an intranet and the internet.

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