Private-Use Networks


Private-Use Networks is a network that uses private IP Address space, following the standards set by RFC 1918 for Internet Protocol Version 4 (IPv4), and RFC 4193 for Internet Protocol Version 6 (IPv6).

These addresses are commonly used for home, office, and enterprise Local Area Networks (LANs).

Private-Use Networks address spaces were originally defined in an effort to delay IPv4 address exhaustion, but they are also a feature of IPv6 where exhaustion is not an issue.

The Internet Engineering Task Force (IETF) has directed the Internet Assigned Numbers Authority (IANA) to reserve the following IPv4 address ranges for private networks, as published in RFC 1918:[1]

RFC 1918 nameIP Address rangenumber of addresseslargest CIDR block (subnet mask)host id sizemask bitsclassful description
24-bit block10.0.0.0 –,777,21610.0.0.0/8 ( bits8 bitssingle class A network
20-bit block172.16.0.0 –,048,576172.16.0.0/12 ( bits12 bits16 contiguous class B networks
16-bit block192.168.0.0 –,536192.168.0.0/16 ( bits16 bits256 contiguous class C networks
N-A100.64.0.1- ( bits10 bitsCarrier-grade NAT

Carrier-grade Network Address Translation#

Carrier-grade NAT (CGN) is defined in RFC 6598 allocated This IP Address block should not be used either on Private-Use Networks or on the public Internet

Private IPv6 addresses#

Private IPv6 addresses is described in Unique Local IPv6 Unicast Addresses (RFC 4193)

Private-Use Networks Summary Table#

Address BlockPresent UseReference"This" NetworkRFC 1122, Section NetworksRFC 1918 1122, Section LocalRFC 3927 NetworksRFC 1918 Protocol AssignmentsRFC 5736 5737 Relay AnycastRFC 3068 NetworksRFC 1918 Interconnect
Device Benchmark Testing
RFC 2544 5737 5737 3171 for Future UseRFC 1112, Section 4 BroadcastRFC 919, Section 7
RFC 922, Section 7 NAT (CGN)RFC 6598

More Information#

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