df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsInternet Engineering Task Force Akira Kato, WIDE
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsINTERNET-DRAFT Paul Vixie, ISC
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsExpires: August 24, 2003 February 24, 2003
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Operational Guidelines for "local" zones in the DNS
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsStatus of this Memo
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThis document is an Internet-Draft and is in full conformance with all
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsprovisions of Section 10 of RFC2026.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsInternet-Drafts are working documents of the Internet Engineering Task
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsForce (IETF), its areas, and its working groups. Note that other groups
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsmay also distribute working documents as Internet-Drafts.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsInternet-Drafts are draft documents valid for a maximum of six months
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsand may be updated, replaced, or obsoleted by other documents at any
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewstime. It is inappropriate to use Internet-Drafts as reference material
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsor to cite them other than as ``work in progress.''
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsTo view the list Internet-Draft Shadow Directories, see
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsDistribution of this memo is unlimited.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThe internet-draft will expire in 6 months. The date of expiration will
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsbe August 24, 2003.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsA large number of DNS queries regarding to the "local" zones are sent
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsover the Internet in every second. This memo describes operational
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsguidelines to reduce the unnecessary DNS traffic as well as the load of
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsthe Root DNS Servers.
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews1. Introduction
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsWhile it has yet been described in a RFC, .local is used to provide a
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewslocal subspace of the DNS tree. Formal delegation process has not been
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewscompleted for this TLD. In spite of this informal status, .local has
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsbeen used in many installations regardless of the awareness of the
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsusers. Usually, the local DNS servers are not authoritative to the
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews.local domain, they end up to send queries to the Root DNS Servers.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThere are several other DNS zones which describe the "local"
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsinformation. .localhost has been used to describe the localhost for
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsmore than a couple of decades and virtually all of the DNS servers are
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsconfigured authoritative for .localhost and its reverse zone .127.in-
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsKATO Expires: August 24, 2003 [Page 1]
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsDRAFT DNS local zones February 2003
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsaddr.arpa. However, there are other "local" zones currently used in the
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsInternet or Intranets connected to the Internet through NATs or similar
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsAt a DNS server of an university in Japan, half of the DNS queries sent
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsto one of the 13 Root DNS Servers were regarding to the .local. At
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsanother DNS Server running in one of the Major ISPs in Japan, the 1/4
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewswere .local. If those "local" queries are able to direct other DNS
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsservers than Root, or they can be resolved locally, it contributes the
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsreduction of the Root DNS Servers.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsAny DNS queries regarding to "local" names should not be sent to the DNS
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsservers on the Internet.
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews3. Operational Guidelines
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThose queries should be processed at the DNS servers internal to each
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewssite so that the severs respond with NXDOMAIN rather than sending
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsqueries to the DNS servers outside.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThe "local" names have common DNS suffixes which are listed below:
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews3.1. Local host related zones:
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsFollowing two zones are described in [Barr, 1996] and .localhost is also
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsdefined in [Eastlake, 1999] .
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews o .localhost
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsFollowing two zones are for the loopback address in IPv6 [Hinden, 1998]
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews. While the TLD for IPv6 reverse lookup is .arpa as defined in [Bush,
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews2001] , the old TLD .int has been used for this purpose for years
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews[Thomson, 1995] and many implementations still use .int. So it is
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewssuggested that both zones should be provided for each IPv6 reverse
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewslookup zone for a while.
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews o 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.int
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews o 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews3.2. Locally created name space
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsWhile the use of .local has been proposed in several Internet-Drafts, it
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewshas not been described in any Internet documents with formal status.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsHowever, the amount of the queries for .local is much larger than
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsothers, it is suggested to resolve the following zone locally:
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsKATO Expires: August 24, 2003 [Page 2]
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsDRAFT DNS local zones February 2003
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews3.3. Private or site-local addresses
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThe following IPv4 "private" addresses [Rekhter, 1996] and IPv6 site-
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewslocal addresses [Hinden, 1998] should be resolved locally:
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews3.4. Link-local addresses
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThe link-local address blocks for IPv4 [IANA, 2002] and IPv6 [Hinden,
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews1998] should be resolved locally:
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsKATO Expires: August 24, 2003 [Page 3]
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsDRAFT DNS local zones February 2003
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews4. Suggestions to developers
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews4.1. Suggestions to DNS software implementors
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsIn order to avoid unnecessary traffic, it is suggested that DNS software
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsimplementors provide configuration templates or default configurations
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsso that the names described in the previous section are resolved locally
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsrather than sent to other DNS servers in the Internet.
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews4.2. Suggestions to developers of NATs or similar devices
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThere are many NAT or similar devices available in the market.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsRegardless of the availability of DNS Servers in those devices, it is
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewssuggested that those devices are able to filter the DNS traffic or
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsrespond to the DNS traffic related to "local" zones by configuration
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsregardless of its ability of DNS service. It is suggested that this
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsfunctionality is activated by default.
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews5. IANA Consideration
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsWhile .local TLD has yet defined officially, there are substantial
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsqueries to the Root DNS Servers as of writing. About 1/4 to 1/2% of the
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewstraffic sent to the Root DNS Servers are related to the .local zone.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsTherefore, while it is not formally defined, it is suggested that IANA
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsdelegates .local TLD to an organization.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThe AS112 Project [Vixie, ] serves authoritative DNS service for RFC1918
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsaddress and the link-local address. It has several DNS server instances
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrewsaround the world by using BGP Anycast [Hardie, 2002] . So the AS112
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsProject is one of the candidates to host the .local TLD.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsAuthors' addresses
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews The University of Tokyo, Information Technology Center
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews 2-11-16 Yayoi Bunkyo
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Tokyo 113-8658, JAPAN
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Tel: +81 3-5841-2750
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Email: kato@wide.ad.jp
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Internet Software Consortium
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews 950 Charter Street
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Redwood City, CA 94063, USA
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Tel: +1 650-779-7001
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews Email: vixie@isc.org
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsKATO Expires: August 24, 2003 [Page 4]
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsDRAFT DNS local zones February 2003
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsD. Barr, "Common DNS Operational and Configuration Errors" in RFC1912
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews(February 1996).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsEastlake, 1999.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsD. Eastlake, "Reserved Top Level DNS Names" in RFC2606 (June 1999).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsHinden, 1998.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsR. Hinden and S. Deering, "IP Version 6 Addressing Architecture" in
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsRFC2373 (July 1998).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsR. Bush, "Delegation of IP6.ARPA" in RFC3152 (August 2001).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsThomson, 1995.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsS. Thomson and C. Huitema, "DNS Extensions to support IP version 6" in
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsRFC1886 (December 1995).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsRekhter, 1996.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsY. Rekhter, B. Moskowitz, D. Karrenberg, G. J. de Groot, and E. Lear,
df4c20903e3a291a1f784992846c0400189b04a7Mark Andrews"Address Allocation for Private Internets" in RFC1918 (February 1996).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsIANA, "Special-Use IPv4 Addresses" in RFC3330 (September 2002).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsP. Vixie, "AS112 Project" in AS112. http://www.as112.net/.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsHardie, 2002.
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsT. Hardie, "Distributing Authoritative Name Servers via Shared Unicast
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsAddresses" in RFC3258 (April 2002).
df4c20903e3a291a1f784992846c0400189b04a7Mark AndrewsKATO Expires: August 24, 2003 [Page 5]