# Private Internet Address Allocation

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Private Address Space

The Internet Assigned Numbers Authority (IANA) has reserved the following blocks of IP address space for private internal networks:

  10.0.0.0 - 10.255.255.255
  172.16.0.0 - 172.31.255.255
  192.168.0.0 - 192.168.255.255

The first block is a single class A network number, the second block is a set of 16 contiguous class B network numbers, and the third block is a set of 255 contiguous class C network numbers.

Use private address space, you don't need to coordinate with the Internet registry. Addresses within this private address space are only unique within your network. Remember, if you need globally unique address space, you must obtain addresses from an Internet registry.

Last Updated: 12 August 1996