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4117. [protocol] Add EMPTY.AS112.ARPA as per RFC 7534.
(cherry picked from commit 8f20f6c9d7)
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4117. [protocol] Add EMPTY.AS112.ARPA as per RFC 7534.
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4113. [test] Check for Net::DNS is some system test
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prerequisites. [RT #39369]
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@ -352,6 +352,9 @@ const char *empty_zones[] = {
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/* Example Prefix, RFC 3849. */
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"8.B.D.0.1.0.0.2.IP6.ARPA",
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/* RFC 7534 */
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"EMPTY.AS112.ARPA",
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NULL
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};
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@ -159,3 +159,5 @@
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6844: DNS Certification Authority Authorization (CAA) Resource Record
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6891: Extension Mechanisms for DNS (EDNS(0))
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7314: Extension Mechanisms for DNS (EDNS) EXPIRE Option
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7534: AS112 Nameserver Operations
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7535: AS112 Redirection Using DNAME
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1347
doc/rfc/rfc7534.txt
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1347
doc/rfc/rfc7534.txt
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Load diff
899
doc/rfc/rfc7535.txt
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doc/rfc/rfc7535.txt
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Internet Engineering Task Force (IETF) J. Abley
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Request for Comments: 7535 Dyn, Inc.
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Category: Informational B. Dickson
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ISSN: 2070-1721 Twitter, Inc.
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W. Kumari
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Google
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G. Michaelson
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APNIC
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May 2015
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AS112 Redirection Using DNAME
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Abstract
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AS112 provides a mechanism for handling reverse lookups on IP
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addresses that are not unique (e.g., RFC 1918 addresses). This
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document describes modifications to the deployment and use of AS112
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infrastructure that will allow zones to be added and dropped much
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more easily, using DNAME resource records.
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This approach makes it possible for any DNS zone administrator to
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sink traffic relating to parts of the global DNS namespace under
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their control to the AS112 infrastructure without coordination with
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the operators of AS112 infrastructure.
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Status of This Memo
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This document is not an Internet Standards Track specification; it is
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published for informational purposes.
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This document is a product of the Internet Engineering Task Force
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(IETF). It represents the consensus of the IETF community. It has
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received public review and has been approved for publication by the
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Internet Engineering Steering Group (IESG). Not all documents
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approved by the IESG are a candidate for any level of Internet
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Standard; see Section 2 of RFC 5741.
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Information about the current status of this document, any errata,
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and how to provide feedback on it may be obtained at
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http://www.rfc-editor.org/info/rfc7535.
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Abley, et al. Informational [Page 1]
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RFC 7535 AS112 Redirection Using DNAME May 2015
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Copyright Notice
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Copyright (c) 2015 IETF Trust and the persons identified as the
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document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
|
||||
Provisions Relating to IETF Documents
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(http://trustee.ietf.org/license-info) in effect on the date of
|
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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
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the Trust Legal Provisions and are provided without warranty as
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described in the Simplified BSD License.
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Table of Contents
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1. Introduction ....................................................3
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2. Design Overview .................................................4
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3. AS112 Operations ................................................5
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3.1. Extensions to Support DNAME Redirection ....................5
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3.2. Redirection of Query Traffic to AS112 Servers ..............5
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4. Continuity of AS112 Operations ..................................6
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5. Candidate Zones for AS112 Redirection ...........................6
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6. DNAME Deployment Considerations .................................7
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7. IAB Statement Regarding This .ARPA Request ......................8
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8. IANA Considerations .............................................8
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8.1. Address Assignment .........................................8
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8.2. Hosting of AS112.ARPA .....................................10
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8.3. Delegation of AS112.ARPA ..................................10
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9. Security Considerations ........................................10
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10. References ....................................................11
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10.1. Normative References .....................................11
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10.2. Informative References ...................................11
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Appendix A. Assessing Support for DNAME in the Real World .........13
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A.1. Methodology ................................................13
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A.2. Results ....................................................15
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Acknowledgements ..................................................16
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Authors' Addresses ................................................16
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Abley, et al. Informational [Page 2]
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RFC 7535 AS112 Redirection Using DNAME May 2015
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1. Introduction
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Many sites connected to the Internet make use of IPv4 addresses that
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are not globally unique. Examples are the addresses designated in
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[RFC1918] for private use within individual sites.
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Devices in such environments may occasionally originate Domain Name
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System (DNS) queries (so-called "reverse lookups") corresponding to
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those private-use addresses. Since the addresses concerned have only
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local significance, it is good practice for site administrators to
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ensure that such queries are answered locally. However, it is not
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uncommon for such queries to follow the normal delegation path in the
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public DNS instead of being answered within the site.
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It is not possible for public DNS servers to give useful answers to
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such queries. In addition, due to the wide deployment of private-use
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addresses and the continuing growth of the Internet, the volume of
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such queries is large and growing. The AS112 project aims to provide
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a distributed sink for such queries in order to reduce the load on
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the IN-ADDR.ARPA authoritative servers. The AS112 project is named
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after the Autonomous System Number (ASN) that was assigned to it.
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Prior to implementation of this technique, the AS112 project did not
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accommodate the addition and removal of DNS zones elegantly. Since
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additional zones of definitively local significance are known to
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exist, this presents a problem. This document describes
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modifications to the deployment and use of AS112 infrastructure that
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will allow zones to be added and dropped much more easily.
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The AS112 project is described in detail in [RFC7534].
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The AS112 nameservers (PRISONER.IANA.ORG, BLACKHOLE-1.IANA.ORG, and
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BLACKHOLE-2.IANA.ORG) are required to answer authoritatively for each
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and every zone that is delegated to them. If a zone is delegated to
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AS112 nameservers without those nameservers being configured ahead of
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time to answer authoritatively for that zone, there is a detrimental
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impact on clients following referrals for queries within that zone.
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This misconfiguration is colloquially known as a "lame delegation".
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AS112 nameserver operators are only loosely coordinated, and hence
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adding support for a new zone (or, correspondingly, removing support
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for a zone that is no longer delegated to the AS112 nameservers) is
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difficult to accomplish with accuracy. Testing AS112 nameservers
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remotely to see whether they are configured to answer authoritatively
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for a particular zone is similarly challenging, since AS112 nodes are
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distributed using anycast [RFC4786].
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Abley, et al. Informational [Page 3]
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RFC 7535 AS112 Redirection Using DNAME May 2015
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This document defines a more flexible approach for sinking queries on
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AS112 infrastructure that can be deployed alongside unmodified,
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existing AS112 nodes. Instead of delegating additional zones
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directly to AS112 nameservers, DNAME [RFC6672] redirection is used.
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This approach has the advantage that query traffic for arbitrary
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parts of the namespace can be directed to AS112 servers without those
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servers having to be reconfigured every time a zone is added or
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removed.
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This approach makes it possible for any DNS zone administrator to
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sink traffic relating to parts of the global DNS namespace under
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their control to the AS112 infrastructure without coordination with
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the operators of AS112 infrastructure.
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2. Design Overview
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A new zone, EMPTY.AS112.ARPA, is delegated to a single nameserver
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BLACKHOLE.AS112.ARPA (IPv4 address 192.31.196.1, IPv6 address
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2001:4:112::1).
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The IPv4 address 192.31.196.1 has been selected from the prefix
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assigned by the IANA such that the address is coverable by a single
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IPv4 /24 prefix, and that no other address covered by that prefix is
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in use. The IPv6 address 2001:4:112::1 has been similarly assigned
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such that no other address within a covering /48 is in use. This
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addressing plan accommodates the anycast distribution of the
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BLACKHOLE.AS112.ARPA service using a single IPv4 service prefix and a
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single IPv6 service prefix. See [RFC4786] for more discussion of
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anycast service distribution; see Section 8 for the specific actions
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completed by IANA per this document.
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Some or all of the existing AS112 nodes should be extended to support
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these new nameserver addresses and to host the EMPTY.AS112.ARPA zone.
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See [RFC7534] for revised guidance to AS112 server operators.
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Each part of the DNS namespace for which it is desirable to sink
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queries at AS112 nameservers should be redirected to the
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EMPTY.AS112.ARPA zone using DNAME [RFC6672]. See Section 3.2 for
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guidance to zone administrators.
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Abley, et al. Informational [Page 4]
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RFC 7535 AS112 Redirection Using DNAME May 2015
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3. AS112 Operations
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|
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3.1. Extensions to Support DNAME Redirection
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Guidance to operators of AS112 nodes is extended to include
|
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configuration of the 192.31.196.1 and 2001:4:112::1 addresses, and
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the corresponding announcement of covering routes for those
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addresses, and to host the EMPTY.AS112.ARPA zone.
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IPv4-only AS112 nodes should only configure the 192.31.196.1
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nameserver address; IPv6-only AS112 nodes should only configure the
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2001:4:112::1 nameserver address.
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It is only necessary for a single AS112 server operator to implement
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these extensions for this mechanism to function as intended. It is
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beneficial if many more than one AS112 server operator makes these
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changes, however, since that provides for greater distribution and
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capacity for the nameservers serving the EMPTY.AS112.ARPA zone. It
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is not necessary for all AS112 server operators to make these changes
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for the mechanism to be viable.
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Detailed instructions for the implementation of these extensions are
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included in [RFC7534].
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|
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3.2. Redirection of Query Traffic to AS112 Servers
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Once the EMPTY.AS112.ARPA zone has been deployed using the
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nameservers described in Section 3.1, redirections may be installed
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in the DNS namespace for queries that are intended to be answered by
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the AS112 infrastructure.
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For example, reverse queries corresponding to TEST-NET-1
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(192.0.2.0/24) [RFC5737] could be redirected to AS112 nameservers by
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installing a DNAME resource record in the 192.IN-ADDR.ARPA zone, as
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illustrated in Figure 1.
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$ORIGIN 192.IN-ADDR.ARPA.
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...
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2.0 IN DNAME EMPTY.AS112.ARPA.
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...
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Figure 1
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There is no practical limit to the number of redirections that can be
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configured in this fashion. Redirection of a particular part of the
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namespace to EMPTY.AS112.ARPA can be removed at any time, under the
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control of the administrators of the corresponding part of the DNS
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namespace. No changes to deployed AS112 nodes incorporating the
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Abley, et al. Informational [Page 5]
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RFC 7535 AS112 Redirection Using DNAME May 2015
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extensions described in this document are required to support
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additional redirections. A list of possible candidates for AS112
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redirection can be found in Section 5.
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DNAME resource records deployed for this purpose can be signed with
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DNSSEC [RFC4033], providing a secure means of authenticating the
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legitimacy of each redirection.
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4. Continuity of AS112 Operations
|
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|
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Existing guidance to AS112 server operators to accept and respond to
|
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queries directed at the PRISONER.IANA.ORG, BLACKHOLE-1.IANA.ORG, and
|
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BLACKHOLE-2.IANA.ORG nameservers should continue to be followed, and
|
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no changes to the delegation of existing zones hosted on AS112
|
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servers should occur. These measures are intended to provide
|
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continuity of operations for zones currently delegated to AS112
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servers and avoid any accidental client impact due to the changes
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proposed in this document.
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Once it has become empirically and quantitatively clear that the
|
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EMPTY.AS112.ARPA zone is well hosted to the extent that it is thought
|
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that the existing, unmodified AS112 servers host 10.IN-ADDR.ARPA, the
|
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decision might be made to replace the delegation of those [RFC1918]
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zones with DNAME redirection. Once implemented, the
|
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PRISONER.IANA.ORG, BLACKHOLE-1.IANA.ORG, and BLACKHOLE-2.IANA.ORG
|
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nameservers could be retired. This document gives no such direction
|
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to the IANA, however.
|
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|
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5. Candidate Zones for AS112 Redirection
|
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|
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All zones listed in [RFC6303] are candidates for AS112 redirection.
|
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|
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Since no pre-provisioning is required on the part of AS112 operators
|
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to facilitate sinking of any name in the DNS namespace by AS112
|
||||
infrastructure, this mechanism supports AS112 redirection by any zone
|
||||
owner in the DNS.
|
||||
|
||||
This document is simply concerned with provision of the AS112
|
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redirection service and does not specify that any particular AS112
|
||||
redirection be put in place.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
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|
||||
|
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Abley, et al. Informational [Page 6]
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RFC 7535 AS112 Redirection Using DNAME May 2015
|
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|
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|
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6. DNAME Deployment Considerations
|
||||
|
||||
DNAME was specified years after the original implementations of
|
||||
[RFC1035], and hence universal deployment cannot be expected.
|
||||
[RFC6672] specifies a fallback mechanism that makes use of
|
||||
synthesised CNAME RRSets for this reason. The expectation that
|
||||
design choices in the DNAME specification ought to mitigate any lack
|
||||
of deployment is reviewed below. Experimental validation of those
|
||||
expectations is included in Appendix A.
|
||||
|
||||
It is a fundamental design requirement of AS112 service that
|
||||
responses be cached. We can safely declare DNAME support on the
|
||||
authoritative server to be a prerequisite for DNAME redirection, but
|
||||
the cases where individual elements in resolver chains do not support
|
||||
DNAME processing deserve closer examination.
|
||||
|
||||
The expected behaviour when a DNAME response is supplied to a
|
||||
resolver that does not support DNAME is that the accompanying,
|
||||
synthesised CNAME will be accepted and cached. Re-query frequency
|
||||
will be determined by the TTLs (Time to Live) returned by the
|
||||
DNAME-responding authoritative servers.
|
||||
|
||||
Resolution of the CNAME target is straightforward and functions
|
||||
exactly as the AS112 project has operated since it was deployed. The
|
||||
negative caching [RFC2308] of the CNAME target follows the parameters
|
||||
defined in the target zone, EMPTY.AS112.ARPA. This has the side
|
||||
effects that all redirected names ultimately landing on an AS112 node
|
||||
will be negatively cached with the same parameters, but this lack of
|
||||
flexibility seems non-controversial; the effect of reducing the
|
||||
negative cache TTL would be increased query volume on the AS112 node
|
||||
operator concerned, and hence controls seem well aligned with
|
||||
operation.
|
||||
|
||||
Validating resolvers (i.e., those requesting and processing DNSSEC
|
||||
[RFC4033] metadata) are required to implement DNAME and hence should
|
||||
not make use of synthesised CNAME RRs. The lack of signature over a
|
||||
received CNAME RR should hence not limit the ability to sign the
|
||||
(DNAME) redirection point, and for those (DNAME) signatures to be
|
||||
validated.
|
||||
|
||||
In the case where a recursive server implements DNAME but DNAME is
|
||||
not implemented in a stub resolver, CNAME synthesis will again
|
||||
provide a viable path.
|
||||
|
||||
DNAME support on AS112 nodes themselves is never required under this
|
||||
proposal.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 7]
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|
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RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
7. IAB Statement Regarding This .ARPA Request
|
||||
|
||||
With the publication of this document, the IAB approves of the
|
||||
delegation of 'AS112' in the ARPA domain. Under [RFC3172], the IAB
|
||||
has requested that IANA delegate and provision "AS112.ARPA" as
|
||||
specified in this specification. However, the IAB does not take any
|
||||
architectural or technical position about this specification.
|
||||
|
||||
8. IANA Considerations
|
||||
|
||||
8.1. Address Assignment
|
||||
|
||||
Per this document, IANA has assigned IPv4 and IPv6 number resources
|
||||
in conformance with Section 4 of [RFC2860].
|
||||
|
||||
The IANA has assigned one IPv4 /24 netblock and registered its use in
|
||||
the "IANA IPv4 Special-Purpose Address Registry" [RFC6890] as
|
||||
follows:
|
||||
|
||||
+----------------------+-----------------+
|
||||
| Name | Value |
|
||||
+----------------------+-----------------+
|
||||
| Address Block | 192.31.196.0/24 |
|
||||
| | |
|
||||
| Name | AS112-v4 |
|
||||
| | |
|
||||
| RFC | RFC 7535 |
|
||||
| | |
|
||||
| Allocation Date | 2014-12 |
|
||||
| | |
|
||||
| Termination Date | N/A |
|
||||
| | |
|
||||
| Source | True |
|
||||
| | |
|
||||
| Destination | True |
|
||||
| | |
|
||||
| Forwardable | True |
|
||||
| | |
|
||||
| Global | True |
|
||||
| | |
|
||||
| Reserved-by-Protocol | False |
|
||||
+----------------------+-----------------+
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 8]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
IANA has assigned one IPv6 /48 netblock and registered its use in the
|
||||
"IANA IPv6 Special-Purpose Address Registry" [RFC6890] as follows:
|
||||
|
||||
+----------------------+-----------------+
|
||||
| Name | Value |
|
||||
+----------------------+-----------------+
|
||||
| Address Block | 2001:4:112::/48 |
|
||||
| | |
|
||||
| Name | AS112-v6 |
|
||||
| | |
|
||||
| RFC | RFC 7535 |
|
||||
| | |
|
||||
| Allocation Date | 2014-12 |
|
||||
| | |
|
||||
| Termination Date | N/A |
|
||||
| | |
|
||||
| Source | True |
|
||||
| | |
|
||||
| Destination | True |
|
||||
| | |
|
||||
| Forwardable | True |
|
||||
| | |
|
||||
| Global | True |
|
||||
| | |
|
||||
| Reserved-by-Protocol | False |
|
||||
+----------------------+-----------------+
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 9]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
8.2. Hosting of AS112.ARPA
|
||||
|
||||
The IANA hosts and signs the zone AS112.ARPA using nameservers and
|
||||
DNSSEC signing infrastructure of their choosing, as shown in
|
||||
Figure 2. SOA RDATA may be adjusted by the IANA to suit their
|
||||
operational requirements.
|
||||
|
||||
$ORIGIN AS112.ARPA.
|
||||
$TTL 3600
|
||||
|
||||
@ IN SOA BLACKHOLE.AS112.ARPA. NOC.DNS.ICANN.ORG. (
|
||||
1 ; serial
|
||||
10800 ; refresh
|
||||
3600 ; retry
|
||||
1209600 ; expire
|
||||
3600 ) ; negative cache TTL
|
||||
|
||||
NS A.IANA-SERVERS.NET.
|
||||
NS B.IANA-SERVERS.NET.
|
||||
NS C.IANA-SERVERS.NET.
|
||||
|
||||
BLACKHOLE A 192.31.196.1
|
||||
AAAA 2001:4:112::1
|
||||
|
||||
HOSTNAME NS BLACKHOLE
|
||||
|
||||
EMPTY NS BLACKHOLE
|
||||
|
||||
Figure 2
|
||||
|
||||
8.3. Delegation of AS112.ARPA
|
||||
|
||||
The IANA has arranged delegation from the ARPA zone according to
|
||||
normal IANA procedure for ARPA zone management, to the nameservers
|
||||
used in carrying out the direction in Section 8.2. The whois contact
|
||||
information for the new record is specified by the IAB under
|
||||
[RFC3172].
|
||||
|
||||
9. Security Considerations
|
||||
|
||||
This document presents no known additional security concerns to the
|
||||
Internet.
|
||||
|
||||
For security considerations relating to AS112 service in general, see
|
||||
[RFC7534].
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 10]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
10. References
|
||||
|
||||
10.1. Normative References
|
||||
|
||||
[RFC1035] Mockapetris, P., "Domain names - implementation and
|
||||
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
|
||||
November 1987, <http://www.rfc-editor.org/info/rfc1035>.
|
||||
|
||||
[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS
|
||||
NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998,
|
||||
<http://www.rfc-editor.org/info/rfc2308>.
|
||||
|
||||
[RFC6672] Rose, S. and W. Wijngaards, "DNAME Redirection in the
|
||||
DNS", RFC 6672, DOI 10.17487/RFC6672, June 2012,
|
||||
<http://www.rfc-editor.org/info/rfc6672>.
|
||||
|
||||
[RFC7534] Abley, J. and W. Sotomayor, "AS112 Nameserver Operations",
|
||||
RFC 7534, DOI 10.17487/RFC7534, May 2015,
|
||||
<http://www.rfc-editor.org/info/rfc7534>.
|
||||
|
||||
10.2. Informative References
|
||||
|
||||
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
|
||||
and E. Lear, "Address Allocation for Private Internets",
|
||||
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
|
||||
<http://www.rfc-editor.org/info/rfc1918>.
|
||||
|
||||
[RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
|
||||
Understanding Concerning the Technical Work of the
|
||||
Internet Assigned Numbers Authority", RFC 2860,
|
||||
DOI 10.17487/RFC2860, June 2000,
|
||||
<http://www.rfc-editor.org/info/rfc2860>.
|
||||
|
||||
[RFC3172] Huston, G., Ed., "Management Guidelines & Operational
|
||||
Requirements for the Address and Routing Parameter Area
|
||||
Domain ("arpa")", BCP 52, RFC 3172, DOI 10.17487/RFC3172,
|
||||
September 2001, <http://www.rfc-editor.org/info/rfc3172>.
|
||||
|
||||
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "DNS Security Introduction and Requirements",
|
||||
RFC 4033, DOI 10.17487/RFC4033, March 2005,
|
||||
<http://www.rfc-editor.org/info/rfc4033>.
|
||||
|
||||
[RFC4786] Abley, J. and K. Lindqvist, "Operation of Anycast
|
||||
Services", BCP 126, RFC 4786, DOI 10.17487/RFC4786,
|
||||
December 2006, <http://www.rfc-editor.org/info/rfc4786>.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 11]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
[RFC5737] Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks
|
||||
Reserved for Documentation", RFC 5737,
|
||||
DOI 10.17487/RFC5737, January 2010,
|
||||
<http://www.rfc-editor.org/info/rfc5737>.
|
||||
|
||||
[RFC6303] Andrews, M., "Locally Served DNS Zones", BCP 163,
|
||||
RFC 6303, DOI 10.17487/RFC6303, July 2011,
|
||||
<http://www.rfc-editor.org/info/rfc6303>.
|
||||
|
||||
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
|
||||
"Special-Purpose IP Address Registries", BCP 153,
|
||||
RFC 6890, DOI 10.17487/RFC6890, April 2013,
|
||||
<http://www.rfc-editor.org/info/rfc6890>.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 12]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
Appendix A. Assessing Support for DNAME in the Real World
|
||||
|
||||
To measure the extent to which the DNAME construct is supported in
|
||||
the Internet, we have used an experimental technique to test the DNS
|
||||
resolvers used by end hosts and derive from the test a measurement of
|
||||
DNAME support within the Internet.
|
||||
|
||||
A.1. Methodology
|
||||
|
||||
The test was conducted by loading a user's browser with four URLs
|
||||
to retrieve. The first three comprise the test setup, while the
|
||||
final URL communicates the result to the experiment controller.
|
||||
The URLs are:
|
||||
|
||||
A http://a.<unique_string>.dname.example.com/1x1.png?
|
||||
a.<unique_string>.dname
|
||||
|
||||
B http://b.dname.example.com/1x1.png?
|
||||
b.<unique_string>.dname
|
||||
|
||||
C http://c.<unique_string>.target.example.net/1x1.png?
|
||||
c.<unique_string>.target
|
||||
|
||||
D http://results.recorder.example.net/1x1.png?
|
||||
results.<unique_string>?za=<a_result>&zb=<b_result>&zc=<c_result>
|
||||
|
||||
The A URL is designed to test the end user's capability to resolve a
|
||||
name that has never been seen before, so that the resolution of this
|
||||
domain name will reliably result in a query at the authoritative
|
||||
nameserver. This is intended to test the use of domain names where
|
||||
there is a dynamic component that also uses the DNAME construct.
|
||||
|
||||
The B URL is deliberately designed to be cached by caching resolvers
|
||||
that are used in the process of resolving the domain name.
|
||||
|
||||
The C URL is a control URL. This is a unique URL, similar to A, but
|
||||
does not refer to a DNAME structure.
|
||||
|
||||
The D URL uses a static cacheable domain name.
|
||||
|
||||
The <unique_string> value is common to the four URLs used in each
|
||||
individual instance of this test but varies from test to test. The
|
||||
result is that each end user is presented with a unique string.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 13]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
The contents of the EXAMPLE.COM, TARGET.EXAMPLE.NET, and
|
||||
RECORDER.EXAMPLE.NET zones are shown in Figure 3.
|
||||
|
||||
$ORIGIN EXAMPLE.COM.
|
||||
...
|
||||
DNAME. IN DNAME TARGET.EXAMPLE.NET.
|
||||
...
|
||||
|
||||
$ORIGIN TARGET.EXAMPLE.NET.
|
||||
...
|
||||
B IN A 192.0.2.0
|
||||
* IN A 192.0.2.0
|
||||
...
|
||||
|
||||
$ORIGIN RECORDER.EXAMPLE.NET.
|
||||
...
|
||||
RESULTS IN A 192.0.2.0
|
||||
...
|
||||
|
||||
Figure 3
|
||||
|
||||
The first three URLs (A, B, and C) are loaded as tasks into the
|
||||
user's browser upon execution of the test's script. The script
|
||||
starts a timer with each of these URLs to measure the elapsed time to
|
||||
fetch the URL. The script then waits for the three fetches to
|
||||
complete, or 10 seconds, whichever occurs first. The script then
|
||||
loads the results of the three timers into the GET arguments of the
|
||||
D URL and performs a fetch to pass these results back to the
|
||||
experiment's server.
|
||||
|
||||
Logs on the web server reached at RESULTS.RECORDER.EXAMPLE.NET will
|
||||
include entries of the form shown in Figure 4. If any of the URLs
|
||||
fail to load within 10 seconds, the D URL will report the failure as
|
||||
a "null" timer value.
|
||||
|
||||
GET /1x1.png?results.<unique_string>?za=1822&zb=1674&zc=1582
|
||||
GET /1x1.png?results.<unique_string>?za=null&zb=null&zc=161
|
||||
|
||||
Figure 4
|
||||
|
||||
The script has been encoded in Adobe Flash with a simple image in the
|
||||
form of an online advertisement. An online advertisement network has
|
||||
been used to distribute the script. The script is invoked when the
|
||||
advertisement is presented in the end user's browser or application
|
||||
and does not require the user to click on the supplied image in any
|
||||
way. The advertisement placement parameters were set to the broadest
|
||||
possible scope to sample users from across the entire Internet.
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 14]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
A.2. Results
|
||||
|
||||
The test was loaded into an advertisement distributed on 2013-10-10
|
||||
and 2013-10-11.
|
||||
|
||||
+--------------------+---------+------------+
|
||||
| | Count | Percentage |
|
||||
+--------------------+---------+------------+
|
||||
| Recorded Results: | 338,478 | |
|
||||
| | | |
|
||||
| A or B Loaded: | 331,896 | 98.1% |
|
||||
| | | |
|
||||
| A Fail and B Fail: | 6,492 | 1.9% |
|
||||
| | | |
|
||||
| A Fail and B Load: | 4,249 | 1.3% |
|
||||
| | | |
|
||||
| A Load and B Fail: | 1,624 | 0.5% |
|
||||
| | | |
|
||||
| C Fail: | 9,355 | 2.8% |
|
||||
+--------------------+---------+------------+
|
||||
|
||||
Table 1
|
||||
|
||||
These results indicate that at most 1.9% of tested clients use DNS
|
||||
resolvers that fail to resolve a domain name that contains a DNAME
|
||||
redirection. However, the failure rate of slightly lower than 3% for
|
||||
the control URL indicates that the failure rate for the DNAME
|
||||
construct lies within the bounds of error within the experimental
|
||||
framework. We conclude that there is no evidence of a consistent
|
||||
failure on the part of deployed DNS resolvers to correctly resolve a
|
||||
DNAME construct.
|
||||
|
||||
This experiment was conducted by Geoff Huston and George Michaelson.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 15]
|
||||
|
||||
RFC 7535 AS112 Redirection Using DNAME May 2015
|
||||
|
||||
|
||||
Acknowledgements
|
||||
|
||||
The authors acknowledge the valuable contributions of Bob Harold and
|
||||
other participants in the DNSOP working group in the preparation of
|
||||
this document.
|
||||
|
||||
Authors' Addresses
|
||||
|
||||
Joe Abley
|
||||
Dyn, Inc.
|
||||
103-186 Albert Street
|
||||
London, ON N6A 1M1
|
||||
Canada
|
||||
|
||||
Phone: +1 519 670 9327
|
||||
EMail: jabley@dyn.com
|
||||
|
||||
|
||||
Brian Dickson
|
||||
Twitter, Inc.
|
||||
|
||||
EMail: bdickson@twitter.com
|
||||
|
||||
|
||||
Warren Kumari
|
||||
Google
|
||||
1600 Amphitheatre Parkway
|
||||
Mountain View, CA 94043
|
||||
United States
|
||||
|
||||
EMail: warren@kumari.net
|
||||
|
||||
|
||||
George Michaelson
|
||||
APNIC
|
||||
|
||||
EMail: ggm@apnic.net
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Abley, et al. Informational [Page 16]
|
||||
|
||||
Loading…
Reference in a new issue