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What are the private IP address ranges?

Bobby Jack
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cvs
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2 Answers2

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You will find the answers to this in RFC 1918. Though, I have listed them below for you.

 10.0.0.0        -   10.255.255.255  (10/8 prefix)
 172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
 192.168.0.0     -   192.168.255.255 (192.168/16 prefix)

It is a common misconception that 169.254.0.0/16 is a private IP address block. This is not true. It is link local, basically it is meant to be only used within networks, but it isn't official RFC1918. Additional information about IPv4 addresses can be found in RFC 3300.

On the other hand IPv6 doesn't have an equivalent to RFC1918, but any sort of site-local work should be done in fc00::/7. This is further touched on in RFC 4193.

Sargun Dhillon
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  • Note that, commonly, 192.168.x.y is treated as a collection of 256 class C (/24) networks... – Roger Lipscombe Feb 09 '09 at 10:55
  • Well, same would be said about the 16 C-nets in 172.16.0.0/12 to. But actually it isn't any more, unless you talk about old A, B and C-class address ranges. But with CIDR we don't do that any more (unless handling *very* old and outdated devices). I do also belive that the site-local addresses isn't in use any more in IPv6. There are other mechanisms in place nowdays, see RFC 4291. http://www.faqs.org/rfcs/rfc4291.html – Anders Sep 19 '14 at 12:39
  • And as noted in the other answer, the information about IPv4 addresses is in RFC5735, not RFC330. RFC330 is about registrated port numbers and not IPv4 addresses. – Anders Sep 19 '14 at 12:44
  • About IPv6 I did missed that it **was not** _site-local addresses_ which are deprecated in RFC 3879 and it actually **was** _unique-local addresses_ which are defined in RFC 4193. Sorry about that. – Anders Nov 09 '14 at 17:06
  • But, `RFC 3300`, you might have wanted to use `RFC 3330` which is obsoleted reference to IPv4 addresses. Use instead `RFC 5735` for how IPv4 address ranges works: http://tools.ietf.org/html/rfc5735 – Anders Nov 09 '14 at 17:09
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also, 169.254.0.0 - 169.254.255.255 are reserved for automatic private IP addressing. Refer to Link-local address wikipedia article

Muxa
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  • That is reserved for link local addresses, not private addreses. – Anders Sep 12 '14 at 22:55
  • Good point. I found on Wikipedia "Microsoft refers to this address autoconfiguration method as Automatic Private IP Addressing (APIPA)" – Muxa Sep 15 '14 at 21:29
  • Yes, and the references are RFC:s and not MS or any others web pages. Even though they are very helpful explaining the RFC:s. Relevent RFC:s in this case are RFC 1918, as Sargun Dhillon explained or RFC 5735 for a overview of IPv4 allocations of address spaces. http://www.faqs.org/rfcs/rfc5735.html – Anders Sep 19 '14 at 12:35