RFC 3330

Special-Use IPv4 Addresses

📅 published October 2002, from ietf

Special-Use IPv4 Addresses 🦋

Okay bestie, first the header stuff 💖 This is RFC 3330, filed under the Network Working Group, written by IANA, dated September 2002. Its category is Informational ✨ The header doesn't list any RFCs it obsoletes or updates, so it's a standalone doc 🌸

Status of this Memo 📜

This memo is here to give info to the Internet community 💅 It is not an Internet standard of any kind, just FYI. Distribution is unlimited, so share it with everyone 🫶

Copyright (C) The Internet Society (2002). All Rights Reserved. 🎀

Abstract ✨

So this doc is basically the list of the special global and specialized IPv4 address blocks that the Internet Assigned Numbers Authority (IANA) has handed out 👑 It does not cover the IPv4 space that goes to operators and users through the Regional Internet Registries. It also skips IPv6 addresses and autonomous system numbers, so don't look for those here 🙈

1. Introduction 🌸

Okay so the Internet has always had one central Internet Assigned Numbers Authority (IANA) in charge of handing out the identifiers it needs to run [RFC1174] 🧚 For IPv4 address space, IANA gives chunks to Regional Internet Registries based on what they need. Those registries then assign IPv4 addresses to operators and users in their own regions 💜

Some tiny bits of IPv4 space have been allocated or assigned straight from IANA for global or other specialized purposes 🍓 Those got documented across a bunch of different RFCs and other docs, so this document exists to gather all those scattered references in one place 🌈

IANA has also been designated by the IETF to make assignments that support the Internet Standards Process [RFC2860] 💅 Section 4 of this doc explains how that assignment process works, so go there if you're curious 🦋

2. Global and Other Specialized Address Blocks 💖

Let's get into the blocks, bestie 💅

0.0.0.0/8 🌸

Addresses in this block refer to source hosts on "this" network 🧚 The address 0.0.0.0/32 may be used as a source address for this host on this network. Other addresses within 0.0.0.0/8 may be used to refer to specified hosts on this network [RFC1700, page 4] ✨

10.0.0.0/8 🎀

This block is set aside for use in private networks 🦋 Its intended use is documented in [RFC1918]. Addresses within this block should not appear on the public Internet, so keep them off the public side 🙈

14.0.0.0/8 🍓

This block is set aside for assignments to the international system of Public Data Networks [RFC1700, page 181] 🌈 The registry of assignments within this block can be accessed from the "Public Data Network Numbers" link on the web page at http://www.iana.org/numbers.html 💜 Addresses within this block are assigned to users and should be treated as such.

24.0.0.0/8 🌸

This block was allocated in early 1996 for use in provisioning IP service over cable television systems 📺 IANA was initially involved in making assignments to cable operators, but that job was transferred to American Registry for Internet Numbers (ARIN) in May 2001 👑 Addresses within this block are assigned in the normal manner and should be treated as such.

39.0.0.0/8 ✨

This block was used in the "Class A Subnet Experiment" that started in May 1995, as documented in [RFC1797] 🧪 The experiment is done and this block has been returned to the pool of addresses reserved for future allocation or assignment 💅 So this block no longer has a special use and is subject to allocation to a Regional Internet Registry for assignment in the normal manner. Main character glow-up 🦋

127.0.0.0/8 🔥

This block is assigned for use as the Internet host loopback address 🔁 A datagram sent by a higher level protocol to an address anywhere within this block should loop back inside the host. This is ordinarily implemented using only 127.0.0.1/32 for loopback, but no addresses within this block should ever appear on any network anywhere [RFC1700, page 5] 🙈

128.0.0.0/16 🌷

This block corresponds to the numerically lowest of the former Class B addresses, and it was initially and is still reserved by IANA 🔒 Given the present classless nature of the IP address space, the basis for the reservation no longer applies. Addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner 💜

169.254.0.0/16 🧚

This is the "link local" block 🌿 It is allocated for communication between hosts on a single link. Hosts obtain these addresses by auto-configuration, such as when a DHCP server may not be found 🫶

172.16.0.0/12 🎀

This block is set aside for use in private networks 🦋 Its intended use is documented in [RFC1918]. Addresses within this block should not appear on the public Internet 🙈

191.255.0.0/16 🌸

This block corresponds to the numerically highest of the former Class B addresses, and it was initially and is still reserved by IANA 🔒 Given the present classless nature of the IP address space, the basis for the reservation no longer applies. Addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner 💜

192.0.0.0/24 🌈

This block corresponds to the numerically lowest of the former Class C addresses, and it was initially and is still reserved by IANA 🔒 Given the present classless nature of the IP address space, the basis for the reservation no longer applies. Addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner ✨

192.0.2.0/24 📝

This block is assigned as "TEST-NET" for use in documentation and example code 💻 It is often used together with the domain names example.com or example.net in vendor and protocol documentation. Addresses within this block should not appear on the public Internet 🙈

192.88.99.0/24 🍓

This block is allocated for use as 6to4 relay anycast addresses, according to [RFC3068] 🌐

192.168.0.0/16 🎀

This block is set aside for use in private networks 🦋 Its intended use is documented in [RFC1918]. Addresses within this block should not appear on the public Internet 🙈

198.18.0.0/15 💜

This block has been allocated for use in benchmark tests of network interconnect devices 📊 Its use is documented in [RFC2544].

223.255.255.0/24 🌷

This block corresponds to the numerically highest of the former Class C addresses, and it was initially and is still reserved by IANA 🔒 Given the present classless nature of the IP address space, the basis for the reservation no longer applies. Addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner 💜

224.0.0.0/4 🫧

This block, formerly known as the Class D address space, is allocated for use in IPv4 multicast address assignments 📡 The IANA guidelines for assignments from this space are described in [RFC3171].

240.0.0.0/4 ⚠️

This block, formerly known as the Class E address space, is reserved 🔒 The "limited broadcast" destination address 255.255.255.255 should never be forwarded outside the (sub-)net of the source. The remainder of this space is reserved for future use [RFC1700, page 4] 💀

Heads up: that 255.255.255.255 limited broadcast address is never supposed to leave your own (sub-)net, so don't let it escape the building 🚫💅

Okay that's the first half, bestie 🫶 The summary table, the assignment process in Section 4, and the security and IANA considerations are coming up next in part 2 💖 Stay tuned, it's about to get even more iconic ✨

7. References ✨

okay so bestie, here's the reading list 📚 every reference this doc leans on, with all the details so you can go find them yourself 🔍

  • [RFC1174] Cerf, V., "IAB Recommended Policy on Distributing Internet Identifier Assignment and IAB Recommended Policy Change to Internet 'Connected' Status", RFC 1174, August 1990.
  • [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700, October 1994.
  • [RFC1797] IANA, "Class A Subnet Experiment", RFC 1797, April 1995.
  • [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. J., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, February 1996.
  • [RFC2050] Hubbard, K., Kosters, M., Conrad, D., Karrenberg, D., and J. Postel, "Internet Registry IP Allocation Guidelines", BCP 12, RFC 2050, November 1996.
  • [RFC2434] Narten, T., and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
  • [RFC2544] Bradner, S., and J. McQuaid, "Benchmarking Methodology for Network Interconnect Devices", RFC 2544, March 1999.
  • [RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of Understanding Concerning the Technical Work of the Internet Assigned Numbers Authority", RFC 2860, June 2000.
  • [RFC3068] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers", RFC 3068, June 2001.
  • [RFC3171] Albanna, Z., Almeroth, K., Meyer, D., and M. Schipper, "IANA Guidelines for IPv4 Multicast Address Assignments", BCP 51, RFC 3171, August 2001.
  • [RFC3232] Reynolds, J. Ed., "Assigned Numbers: RFC 1700 is Replaced by an On-line Database", RFC 3232, January 2002.

8. Acknowledgments 💖

so many people gave comments on the draft versions of this doc, which is so sweet 🥹 the IANA wants to give a special shoutout to Scott Bradner, Randy Bush, and Harald Alvestrand for their constructive feedback and comments 🫶 legends, all of them

9. Author's Address 🏡

Here's where the IANA lives 📬

Internet Assigned Numbers Authority (IANA)
4676 Admiralty Way, Suite 330
Marina del Rey, CA 90292-6601

Phone: +1 310-823-9358
Fax:   +1 310-823-8649
EMail: iana@iana.org

Copyright (C) The Internet Society (2002). All Rights Reserved. 🌈

okay, the legal bit, but make it cute: this document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind. The one catch is that the above copyright notice and this paragraph have to be included on all such copies and derivative works 📝

However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations. The exceptions are when it's needed for developing Internet standards, in which case the procedures for copyrights defined in the Internet Standards process must be followed, or when it's required to translate it into languages other than English 🌍

The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. Forever, bestie 💜

This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 😭 no warranties, not even a little, so read it with that in mind 🙈

Acknowledgement 🌸

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