Internet Engineering Task Force (IETF)
Request for Comments: 5737
Updates: 1166
Category: Informational
ISSN: 2070-1721
J. Arkko
M. Cotton
L. Vegoda
January 2010

IPv4 Address Blocks Reserved for Documentation


Three IPv4 unicast address blocks are reserved for use in examples in specifications and other documents. This document describes the use of these blocks.

Status of This Memo

This document is not an Internet Standards Track specification; it is published for informational purposes.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at

Copyright Notice

Copyright © 2010 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

1. Introduction

This document describes three IPv4 address blocks that are provided for use in documentation. The use of designated address ranges for documentation and examples reduces the likelihood of conflicts and confusion arising from the use of addresses assigned for some other purpose.

[RFC1166] reserves the first of the three address blocks, The other two address blocks have recently been allocated for this purpose, primarily to ease the writing of examples involving addresses from multiple networks.

Other documentation ranges have been defined in the IETF, including the IPv6 documentation prefix [RFC3849] and example domain names [RFC2606]. Documentation also makes use of the ranges reserved in [RFC1918].

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, [RFC2119].

3. Documentation Address Blocks

   The blocks (TEST-NET-1), (TEST-NET-2),
   and (TEST-NET-3) are provided for use in

4. Operational Implications

Addresses within the TEST-NET-1, TEST-NET-2, and TEST-NET-3 blocks SHOULD NOT appear on the public Internet and are used without any coordination with IANA or an Internet registry [RFC2050]. Network operators SHOULD add these address blocks to the list of non- routeable address spaces, and if packet filters are deployed, then this address block SHOULD be added to packet filters.

These blocks are not for local use, and the filters may be used in both local and public contexts.

5. The Status of

Note that has been used for some examples in the past. However, this block did not appear in the list of special prefixes in [RFC3330] or its successors, and the block is therefore not reserved for any special purpose. The block can be used for regular address assignments with caution.

6. Security Considerations

This document has no security implications.

7. IANA Considerations

IANA has recorded the allocation of the three address blocks in the IPv4 address registry. No end party is to be assigned these addresses.

8. References

8.1. Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

8.2. Informative References

   [RFC1166]  Kirkpatrick, S., Stahl, M., and M. Recker, "Internet
              numbers", RFC 1166, July 1990.
   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, February 1996.
   [RFC2050]  Hubbard, K., Kosters, M., Conrad, D., Karrenberg, D., and
              BCP 12, RFC 2050, November 1996.
   [RFC2606]  Eastlake, D. and A. Panitz, "Reserved Top Level DNS
              Names", BCP 32, RFC 2606, June 1999.
   [RFC3330]  IANA, "Special-Use IPv4 Addresses", RFC 3330,
              September 2002.
   [RFC3849]  Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix
              Reserved for Documentation", RFC 3849, July 2004.

Appendix A. Acknowledgments

The authors would like to offer a special note of thanks to APNIC, which nominated and for this purpose. The authors would also like to acknowledge that this document inherits material from [RFC3849].

The authors would also like to thank Geoff Huston, Peter Koch, Ulf Olsson, John Klensin, and others for interesting discussions of this topic.

Authors' Addresses

   Jari Arkko
   Jorvas  02420
   Michelle Cotton
   Internet Corporation for Assigned Names and Numbers
   4676 Admiralty Way, Suite 330
   Marina del Rey  90292
   United States of America
   Phone: +1-310-823-9358
   Leo Vegoda
   Internet Corporation for Assigned Names and Numbers
   4676 Admiralty Way, Suite 330
   Marina del Rey  90292
   United States of America
   Phone: +1-310-823-9358