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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchA private IP address is an address reserved for use inside private networks, rather than a globally unique address intended for the public Internet. In IPv4, private addresses come from three specific ranges; IPv6 has a separate local-use category called Unique Local Addresses (ULAs).
What does “private IP address” mean?
A private IP address identifies a device within a private network, such as a home or organization’s network. Its address needs to be unique within that network, but it does not need to be unique across the entire Internet. Separate networks can therefore reuse the same private address.
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RFC 1918 describes these IPv4 addresses as unique only within an enterprise or a set of enterprises that cooperate to communicate over a private network. IANA likewise lists the RFC 1918 blocks as private-use address space: RFC 1918 and IANA IPv4 Special-Purpose Address Registry.
Which IPv4 addresses are private?
RFC 1918 reserves exactly three IPv4 blocks for private use:
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| Prefix | Private address range |
|---|---|
| 10.0.0.0/8 | 10.0.0.0–10.255.255.255 |
| 172.16.0.0/12 | 172.16.0.0–172.31.255.255 |
| 192.168.0.0/16 | 192.168.0.0–192.168.255.255 |
The boundaries matter: not every address beginning with 172 is private. Only addresses from 172.16.0.0 through 172.31.255.255 fall within the RFC 1918 block.
Can separate networks use the same private IP address?
Yes. A home network and an organization’s network can both assign the same private address to a device because the address is only required to be unique within each network. This reuse works as long as the networks remain separate or handle any overlap when they connect.
If networks with overlapping private addresses are interconnected, the overlap may need to be resolved through coordination or address translation. RFC 1918 sets out the private-addressing rules and the limits on exchanging private routes between enterprises.
Is a private IP address reachable from the public Internet?
Private addresses are not intended to be globally routed. RFC 1918 says private-network route information should not be propagated across inter-enterprise links, and packets with private source or destination addresses should not be forwarded across those links. A private address alone therefore does not provide a globally reachable Internet address.
That does not necessarily mean a device cannot use Internet services. RFC 1918 distinguishes direct IP connectivity to outside hosts from access through mediating gateways. A network can provide access to external services through such a gateway even when its devices use private addresses.
Does IPv6 have private IP addresses?
IPv6 does not use the IPv4 ranges above. Its related local-use category is called Unique Local Addresses (ULAs), defined by RFC 4193 under the FC00::/7 prefix. ULAs are intended for local communications and are not expected to be routed on the global Internet. They can be routed within a site, or between a limited set of sites when that routing is explicitly agreed. See RFC 4193 and the IANA IPv6 Address Space Registry.
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| Address family | Local-use address category | Defining specification |
|---|---|---|
| IPv4 | 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 | RFC 1918 |
| IPv6 | Unique Local Addresses (FC00::/7) | RFC 4193 |
Does “private” mean a device is secure?
No. “Private” describes the address’s intended use and routing context; it is not a security guarantee. Whether a device or network is secure depends on its security controls, not simply on whether it has a private address.
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