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rfc:rfc7535

Internet Engineering Task Force (IETF) J. Abley Request for Comments: 7535 Dyn, Inc. Category: Informational B. Dickson ISSN: 2070-1721 Twitter, Inc.

                                                             W. Kumari
                                                                Google
                                                         G. Michaelson
                                                                 APNIC
                                                              May 2015
                   AS112 Redirection Using DNAME

Abstract

 AS112 provides a mechanism for handling reverse lookups on IP
 addresses that are not unique (e.g., RFC 1918 addresses).  This
 document describes modifications to the deployment and use of AS112
 infrastructure that will allow zones to be added and dropped much
 more easily, using DNAME resource records.
 This approach makes it possible for any DNS zone administrator to
 sink traffic relating to parts of the global DNS namespace under
 their control to the AS112 infrastructure without coordination with
 the operators of AS112 infrastructure.

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
 http://www.rfc-editor.org/info/rfc7535.

Abley, et al. Informational [Page 1] RFC 7535 AS112 Redirection Using DNAME May 2015

Copyright Notice

 Copyright (c) 2015 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
 (http://trustee.ietf.org/license-info) 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.

Table of Contents

 1. Introduction ....................................................3
 2. Design Overview .................................................4
 3. AS112 Operations ................................................5
    3.1. Extensions to Support DNAME Redirection ....................5
    3.2. Redirection of Query Traffic to AS112 Servers ..............5
 4. Continuity of AS112 Operations ..................................6
 5. Candidate Zones for AS112 Redirection ...........................6
 6. DNAME Deployment Considerations .................................7
 7. IAB Statement Regarding This .ARPA Request ......................8
 8. IANA Considerations .............................................8
    8.1. Address Assignment .........................................8
    8.2. Hosting of AS112.ARPA .....................................10
    8.3. Delegation of AS112.ARPA ..................................10
 9. Security Considerations ........................................10
 10. References ....................................................11
    10.1. Normative References .....................................11
    10.2. Informative References ...................................11
 Appendix A. Assessing Support for DNAME in the Real World .........13
   A.1. Methodology ................................................13
   A.2. Results ....................................................15
 Acknowledgements ..................................................16
 Authors' Addresses ................................................16

Abley, et al. Informational [Page 2] RFC 7535 AS112 Redirection Using DNAME May 2015

1. Introduction

 Many sites connected to the Internet make use of IPv4 addresses that
 are not globally unique.  Examples are the addresses designated in
 [RFC1918] for private use within individual sites.
 Devices in such environments may occasionally originate Domain Name
 System (DNS) queries (so-called "reverse lookups") corresponding to
 those private-use addresses.  Since the addresses concerned have only
 local significance, it is good practice for site administrators to
 ensure that such queries are answered locally.  However, it is not
 uncommon for such queries to follow the normal delegation path in the
 public DNS instead of being answered within the site.
 It is not possible for public DNS servers to give useful answers to
 such queries.  In addition, due to the wide deployment of private-use
 addresses and the continuing growth of the Internet, the volume of
 such queries is large and growing.  The AS112 project aims to provide
 a distributed sink for such queries in order to reduce the load on
 the IN-ADDR.ARPA authoritative servers.  The AS112 project is named
 after the Autonomous System Number (ASN) that was assigned to it.
 Prior to implementation of this technique, the AS112 project did not
 accommodate the addition and removal of DNS zones elegantly.  Since
 additional zones of definitively local significance are known to
 exist, this presents a problem.  This document describes
 modifications to the deployment and use of AS112 infrastructure that
 will allow zones to be added and dropped much more easily.
 The AS112 project is described in detail in [RFC7534].
 The AS112 nameservers (PRISONER.IANA.ORG, BLACKHOLE-1.IANA.ORG, and
 BLACKHOLE-2.IANA.ORG) are required to answer authoritatively for each
 and every zone that is delegated to them.  If a zone is delegated to
 AS112 nameservers without those nameservers being configured ahead of
 time to answer authoritatively for that zone, there is a detrimental
 impact on clients following referrals for queries within that zone.
 This misconfiguration is colloquially known as a "lame delegation".
 AS112 nameserver operators are only loosely coordinated, and hence
 adding support for a new zone (or, correspondingly, removing support
 for a zone that is no longer delegated to the AS112 nameservers) is
 difficult to accomplish with accuracy.  Testing AS112 nameservers
 remotely to see whether they are configured to answer authoritatively
 for a particular zone is similarly challenging, since AS112 nodes are
 distributed using anycast [RFC4786].

Abley, et al. Informational [Page 3] RFC 7535 AS112 Redirection Using DNAME May 2015

 This document defines a more flexible approach for sinking queries on
 AS112 infrastructure that can be deployed alongside unmodified,
 existing AS112 nodes.  Instead of delegating additional zones
 directly to AS112 nameservers, DNAME [RFC6672] redirection is used.
 This approach has the advantage that query traffic for arbitrary
 parts of the namespace can be directed to AS112 servers without those
 servers having to be reconfigured every time a zone is added or
 removed.
 This approach makes it possible for any DNS zone administrator to
 sink traffic relating to parts of the global DNS namespace under
 their control to the AS112 infrastructure without coordination with
 the operators of AS112 infrastructure.

2. Design Overview

 A new zone, EMPTY.AS112.ARPA, is delegated to a single nameserver
 BLACKHOLE.AS112.ARPA (IPv4 address 192.31.196.1, IPv6 address
 2001:4:112::1).
 The IPv4 address 192.31.196.1 has been selected from the prefix
 assigned by the IANA such that the address is coverable by a single
 IPv4 /24 prefix, and that no other address covered by that prefix is
 in use.  The IPv6 address 2001:4:112::1 has been similarly assigned
 such that no other address within a covering /48 is in use.  This
 addressing plan accommodates the anycast distribution of the
 BLACKHOLE.AS112.ARPA service using a single IPv4 service prefix and a
 single IPv6 service prefix.  See [RFC4786] for more discussion of
 anycast service distribution; see Section 8 for the specific actions
 completed by IANA per this document.
 Some or all of the existing AS112 nodes should be extended to support
 these new nameserver addresses and to host the EMPTY.AS112.ARPA zone.
 See [RFC7534] for revised guidance to AS112 server operators.
 Each part of the DNS namespace for which it is desirable to sink
 queries at AS112 nameservers should be redirected to the
 EMPTY.AS112.ARPA zone using DNAME [RFC6672].  See Section 3.2 for
 guidance to zone administrators.

Abley, et al. Informational [Page 4] RFC 7535 AS112 Redirection Using DNAME May 2015

3. AS112 Operations

3.1. Extensions to Support DNAME Redirection

 Guidance to operators of AS112 nodes is extended to include
 configuration of the 192.31.196.1 and 2001:4:112::1 addresses, and
 the corresponding announcement of covering routes for those
 addresses, and to host the EMPTY.AS112.ARPA zone.
 IPv4-only AS112 nodes should only configure the 192.31.196.1
 nameserver address; IPv6-only AS112 nodes should only configure the
 2001:4:112::1 nameserver address.
 It is only necessary for a single AS112 server operator to implement
 these extensions for this mechanism to function as intended.  It is
 beneficial if many more than one AS112 server operator makes these
 changes, however, since that provides for greater distribution and
 capacity for the nameservers serving the EMPTY.AS112.ARPA zone.  It
 is not necessary for all AS112 server operators to make these changes
 for the mechanism to be viable.
 Detailed instructions for the implementation of these extensions are
 included in [RFC7534].

3.2. Redirection of Query Traffic to AS112 Servers

 Once the EMPTY.AS112.ARPA zone has been deployed using the
 nameservers described in Section 3.1, redirections may be installed
 in the DNS namespace for queries that are intended to be answered by
 the AS112 infrastructure.
 For example, reverse queries corresponding to TEST-NET-1
 (192.0.2.0/24) [RFC5737] could be redirected to AS112 nameservers by
 installing a DNAME resource record in the 192.IN-ADDR.ARPA zone, as
 illustrated in Figure 1.
   $ORIGIN 192.IN-ADDR.ARPA.
   ...
   2.0     IN      DNAME   EMPTY.AS112.ARPA.
   ...
                               Figure 1
 There is no practical limit to the number of redirections that can be
 configured in this fashion.  Redirection of a particular part of the
 namespace to EMPTY.AS112.ARPA can be removed at any time, under the
 control of the administrators of the corresponding part of the DNS
 namespace.  No changes to deployed AS112 nodes incorporating the

Abley, et al. Informational [Page 5] RFC 7535 AS112 Redirection Using DNAME May 2015

 extensions described in this document are required to support
 additional redirections.  A list of possible candidates for AS112
 redirection can be found in Section 5.
 DNAME resource records deployed for this purpose can be signed with
 DNSSEC [RFC4033], providing a secure means of authenticating the
 legitimacy of each redirection.

4. Continuity of AS112 Operations

 Existing guidance to AS112 server operators to accept and respond to
 queries directed at the PRISONER.IANA.ORG, BLACKHOLE-1.IANA.ORG, and
 BLACKHOLE-2.IANA.ORG nameservers should continue to be followed, and
 no changes to the delegation of existing zones hosted on AS112
 servers should occur.  These measures are intended to provide
 continuity of operations for zones currently delegated to AS112
 servers and avoid any accidental client impact due to the changes
 proposed in this document.
 Once it has become empirically and quantitatively clear that the
 EMPTY.AS112.ARPA zone is well hosted to the extent that it is thought
 that the existing, unmodified AS112 servers host 10.IN-ADDR.ARPA, the
 decision might be made to replace the delegation of those [RFC1918]
 zones with DNAME redirection.  Once implemented, the
 PRISONER.IANA.ORG, BLACKHOLE-1.IANA.ORG, and BLACKHOLE-2.IANA.ORG
 nameservers could be retired.  This document gives no such direction
 to the IANA, however.

5. Candidate Zones for AS112 Redirection

 All zones listed in [RFC6303] are candidates for AS112 redirection.
 Since no pre-provisioning is required on the part of AS112 operators
 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
 redirection service and does not specify that any particular AS112
 redirection be put in place.

Abley, et al. Informational [Page 6] RFC 7535 AS112 Redirection Using DNAME May 2015

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] 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]

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