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RFC 8023

Informational
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Report from the Workshop and Prize on Root Causes and Mitigation of Name Collisions

 


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Independent Submission                                         M. Thomas
Request for Comments: 8023
Category: Informational                                        A. Mankin
ISSN: 2070-1721                                               Salesforce
                                                                L. Zhang
                                                                    UCLA
                                                           November 2016


                 Report from the Workshop and Prize on
             Root Causes and Mitigation of Name Collisions

Abstract

   This document provides context and a report on the workshop on "Root
   Causes and Mitigation of Name Collisions", which took place in
   London, United Kingdom, from March 8 to 10, 2014.  The main goal of
   the workshop was to foster a discussion on the causes and potential
   mitigations of domain name collisions.  This report provides a small
   amount of background and context; then, it provides a summary of the
   workshop's discussions.

Status of This Memo

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

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   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/rfc8023.

[Page 2] 
Copyright Notice

   Copyright (c) 2016 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.

Table of Contents

   1. Introduction ....................................................2
   2. Background and Context ..........................................4
      2.1. Brief Update ...............................................6
   3. Workshop Structure ..............................................7
      3.1. Research Findings ..........................................8
      3.2. System Analysis ............................................9
      3.3. Frameworks: Modeling, Analysis, and  Mitigation ............9
      3.4. Conclusions and Next Steps ................................11
   4. Security Considerations ........................................11
   5. Informative References .........................................12
   Appendix A. Program Committee .....................................16
   Appendix B. Workshop Material .....................................16
   Appendix C. Workshop Participants .................................17
   Acknowledgments ...................................................17
   Authors' Addresses ................................................17

1.  Introduction

   It has been well known within the Internet research and engineering
   community that many installed systems in the Internet query the
   domain name system (DNS) root for names under a wide range of top-
   level domains (TLDs).  Many of these TLDs are not delegated, which
   results in a response indicating that the name queried does not exist
   (commonly called an NXDOMAIN response [RFC7719]).  In the Internet
   Corporation for Assigned Names and Numbers (ICANN) community, it was
   observed as early as November 2010 by the Security and Stability
   Advisory Committee (SSAC) report [SAC045] that the addition of new
   TLDs in the DNS root could result in so-called name collisions for
   names used in environments other than the global Internet.  Some
   installed systems, following established (albeit not vetted)
   operational practices, generate queries to the global DNS with name
   suffixes that, under seemingly reasonable assumptions at the time the
   systems were designed or configured, were not expected to be
   delegated as TLDs.  Many of these installed systems depend explicitly

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   or implicitly on the indication from the global DNS that the domain
   name suffix does not exist.  After a new TLD is delegated, the global
   DNS may give a different response to the query involving the TLD than
   it did prior to the TLD's delegation.

   A name collision occurs when an attempt to resolve a name used in a
   private namespace results in a query to the public DNS, and the
   response indicates that the name is in the global DNS [NCRI].  In
   other words, the overlap of public and private namespaces may result
   in potential unintended (and, therefore, potentially harmful)
   resolution results.  The impact of the global change on installed
   systems will be varied; risks to installed systems introduced by name
   collisions may arise due to varied causes.

   In a globally distributed system, such as the Internet, it is
   difficult, yet critical, to agree on policies for demarking
   boundaries of ownership and autonomy.  Name space governance is
   critical to ensure predictable use of names in the global DNS.

   In order to help ensure this uniqueness and interoperability, ICANN,
   through its coordination of the IANA functions, is responsible for
   administration of certain responsibilities associated with Internet
   DNS root zone management, such as generic and country code Top-Level
   Domains (gTLDs and ccTLDs).  Prior to ICANN's creation in 1998, seven
   generic TLDs were defined in the early development of the Internet
   [RFC1591].  Since the formation of ICANN, the delegations of generic,
   internationalized and country code TLDs have been administered and
   delegated by ICANN.  During these delegations, it quickly became
   apparent within the IETF community that there was a need to reserve
   name spaces that can be used for creating limited sets of internal
   names without fear of conflicts with current or future TLD name
   spaces in the global DNS [RFC2606].

   While the reserved TLDs [RFC2606] aimed to enable operators to use
   them only as a small set of reserved names internally, with limited
   uses, educational awareness and operational best practices did not
   achieve the goal of reserving special-use domain names [RFC6761];
   other suffixes, not reserved though at the time not in conflict, were
   often employed instead.  Faulty assumptions, or encouragement in some
   cases by vendor documentation, of "we only use this name internally
   and there is no possibility of leakage to the global DNS" were made
   by numerous operators or administrators.  Numerous reports and
   findings have clearly disproved these faulty assumptions by showing
   substantial "DNS leakage" into the global DNS through mechanisms such
   as search lists.

   In 2012, ICANN created a new gTLD program to add a potentially
   unlimited number of new gTLDs to the root zone as a mechanism to

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   enhance competition, innovation, and consumer choice.  With the
   potential of many new gTLDs becoming delegated in the global DNS,
   operators or administrators who elected to use a non-delegated name
   space internally may face potential "name collision" problems.

   This document is primarily a report on the March 2014 workshop that
   set out to examine the causes and mitigation of such name collisions
   and their associated risks.  It is a companion to the Workshop and
   Prize on Root Causes and Mitigation of Name Collisions proceedings
   [WPNC], and it also provides some additional background and context.

2.  Background and Context

   When the workshop was convened, the context and status of the work
   around name collisions could be described as follows.

   Since early 2008, there had been numerous lengthy discussions within
   the ICANN community about the ability of the DNS root to scale to
   accommodate new gTLDs and the impact of making those changes on the
   DNS ecosystem.  In March 2008, the Internet Architecture Board (IAB)
   observed that the introduction of suffixes in use in a number of
   environments could lead to instability [IAB2008].  In December 2010,
   the Security and Stability Advisory Committee (SSAC) issued their
   report on root scaling in which the committee formalized several
   recommendations based on "actual measurement, monitoring, and data-
   sharing capabilities of root zone performance" to help determine the
   feasibility of root scaling [SAC046].  Separately, the Root Server
   System Advisory Committee [RSSAC] agreed in late 2010 on the need to
   establish standard metrics to be collected and reported by all
   operators.  This effort would provide the community with a baseline
   measure of the entire root server system's performance.  With such an
   established baseline, any possible negative effect from additional
   TLDs within the root could potentially be identified.  In late 2012,
   the ICANN Board affirmed the need to work with the root server
   operators via RSSAC to complete the documentation of the interactions
   between ICANN and the root server operators with respect to root zone
   scaling [IR2012].

   In March 2013, SSAC published an advisory titled "SSAC Advisory on
   Internal Name Certificates," which identified a Certificate Authority
   (CA) practice that, if widely exploited, "could pose a significant
   risk to the privacy and integrity of secure Internet communications"
   [SAC057].  The ICANN Board acknowledged the issues identified in the
   advisory report on internal name certificates [SAC057] as part of a
   more general category of issues.  These issues included installed
   systems utilizing a namespace in a private network that includes a
   non-delegated TLD that is later delegated into the root.  In May
   2013, the ICANN Board commissioned a study on the use within private

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   name spaces of TLDs that are not currently delegated at the root
   level of the global DNS [ISTUDY].  This study was focused on
   potential name collision events between applied-for new gTLDs and
   non-delegated TLDs potentially used in private namespaces.  The study
   also examined the potential possibility of name collisions arising
   from the use of digital certificates referenced in the SSAC report on
   internal name certificates [SAC057].

   Between the RSSAC's and SSAC's advisory statements ([RSSAC] [SAC046])
   and the ICANN commissioning of a study in May 2013, there was
   significant progress on establishing formalized, coordinated
   monitoring and measurement of the root.  RSSAC approached its
   finalization of the specific metrics that each root operator will
   collect and initiated discussions about where the operators will send
   their data for analysis once collected.  To properly gauge the risks
   of new gTLD delegations to the root, an established baseline of
   normal performance of the system would be required to start
   sufficiently ahead of the new delegations.  The execution of these
   RSSAC and SSAC recommendations was timed poorly with the commissioned
   study, resulting in a limited pool of data repositories from which
   any baseline and risk measurements could be established.

   It is common practice for each root operator to monitor its own root
   server, and some operators report the status and performance of their
   services publicly.  As of ICANN's study commissioned in May 2013
   [ISTUDY], there was no mechanism in place to allow a detailed view of
   the entire root system, short of the annual "Day in the Life"
   ([DITL]) data repository, which contains root DNS data over a short
   coordinated time period from a varying subset of root operators and
   was intended to be used for research purposes, not to provide overall
   monitoring and an operational view of system health.  Due to the lack
   of a more comprehensive and desirable data repository for baseline
   and collision analysis DITL has become the de facto referential
   dataset for root traffic analysis.

   The commissioned study, conducted by the Interisle Consulting Group,
   was published in August of 2013.  Their report "Name Collisions in
   the DNS" [INTERISLE], based on [DITL] measurements, addressed name
   collisions in the DNS and also recommended options to mitigate the
   various name collision risks.  The study identified categories of
   strings according to the risk they represent: low risk (80 percent of
   applied-for strings), uncalculated risk (20 percent of applied-for
   strings), and high risk (2 applied-for strings).

   At the same time as the [INTERISLE] study, ICANN published a
   proposal, titled "New gTLD Collision Occurrence Management Plan"
   [NGCOMP], to manage the risk of name collisions within the applied-
   for gTLDs.  Based on measurements, ICANN deemed two strings, .home

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   and .corp, to be high risk because of their widespread use within
   internal networks and would indefinitely delay their delegation
   [INTERISLE].  Those strings within the uncalculated-risk
   classification would be delayed 2 to 3 months in their application
   process while ICANN conducted more research into whether the string
   is of high- or low-risk classification.  Those in the low-risk
   classification would face a delay in activating domains until 120
   days after contracting with ICANN to allow for the change in
   certificate authority practices recommended in the SSAC report on
   internal name certificates [SAC057].

   Within the ICANN proposal [NGCOMP], an approach termed the
   "alternative path to delegation" was outlined, in which a registry
   operator could elect to proceed with delegation, provided it
   initially blocked all second-level domains (SLDs) that appeared in
   the certain DITL datasets pending the completion of the assessment.
   The majority of new gTLD applicants that were eligible elected this
   alternative path once otherwise approved for delegation.  The plan
   also outlined an outreach campaign to educate system administrators,
   software developers, and other engineers about the name collision
   issue and possible mitigation measures.

   As a further provision, the "New gTLD Collision Occurrence Management
   Plan" called for a follow-up study that would develop a "Name
   Collision Occurrence Management Framework" [NCOMF].  In February
   2014, the document, "Mitigating the Risk of DNS Namespace Collisions:
   Phase One Report," was published by the ICANN-contracted group JAS
   Global Advisors [MRDNC].  The report provides a number of
   recommendations for addressing the name collision issue focusing on a
   technique termed "controlled interruption," in which a registry would
   temporarily resolve all SLDs (or all SLDs present in the block list)
   to a specific IP: 127.0.53.53.  The report also makes provisions to
   implement an emergency plan and strategy in case name collisions had
   a "clear danger to human life."

2.1.  Brief Update

   In the time frame after the workshop, a final version of the Phase
   One Report was released in June 2014 [MRDNC].

   In July 2014, after a community review phase, a final recommendation
   was issued by ICANN [NCOMFINAL]; this has been followed by the
   publication of management documents for the implementation of a
   controlled interrupt for new gTLD delegations [NOCA] [NCSLDCIV]
   [ADDNOCA].

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   Much of the framework called for in the Name Collision Occurrence
   Management Framework [NCOMF] was not released by the time of writing
   this document, and the Phase One Report [MRDNC] indicated that its
   publication was delayed due to a security vulnerability [JASBUG]
   identified during the course of the work.

   Broad community efforts to measure the impact of name collisions were
   not included in the final recommendation issued by ICANN [NCOMFINAL].
   At the time of this writing, RSSAC has just published its
   specification of common measurements to be collected by root
   operators, meeting one part of the needs for measurements of the root
   server system [RSSAC002].

3.  Workshop Structure

   The Workshop and Prize on Root Causes and Mitigation of Name
   Collisions [WPNC], sponsored by Verisign, took place March 8-10, 2014
   in London, United Kingdom.  The WPNC was open to the public, and it
   gathered subject-area specialists, researchers, and practitioners to
   discuss and present their views, concerns, and ideas surrounding the
   name collision issue.  Proceedings are published at the workshop's
   website [WPNC].

   The workshop focused on studies of name collision risks and
   mitigations with the expectation to advance the global community's
   insight into operational uses of name suffixes that can result in
   name collisions and to gain a stronger understanding of the potential
   risks for the users of the installed systems.  Additional emphasis
   and attention was given to discussions that might advance the state
   of knowledge about the architecture and impacts of DNS namespaces
   with multiple scopes or resolution contexts and the utilization of
   new methods of monitoring and understanding the needs and methods for
   mitigating emerging Internet risks around name collisions.  A
   technical program committee, whose members spanned a variety of
   organizations and universities, was assembled.  The committee issued
   a call for papers and evaluated all submissions to ensure the highest
   level of quality.

   A synthesis of the accepted papers and conference proceedings is
   captured in the subsections below.  Another informal synopsis of the
   workshop combined with individual statements and observations is
   available online [COMMENTARY].

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3.1.  Research Findings

   Many of the research papers focused on the analysis of DITL data to
   better understand various aspects of the root NXDOMAIN traffic
   ([TECHNIQUES], [RARDBITS], [BLOCKLISTS], [MODELING], and
   [SEARCHLISTS]).  Note: all workshop contributions are listed in
   Appendix B; full papers and slides are available at the website
   [WPNC].

   While the DITL data has become the de facto referential dataset for
   root traffic analysis, some presenters echoed concerns that the
   dataset may have become biased or polluted with "artificial" queries
   after the ICANN "Reveal Day," in which the list of applied-for gTLD
   strings was publicly disclosed.  No conclusive or empirical evidence
   of tampering was presented; however, concerns about the integrity and
   reliability of future DITL collections and analysis for purposes
   related to new gTLDs were echoed by some panelists [IESCPANEL].
   Furthermore, the statistical accuracy and completeness of DITL data
   -- used to draw inferential conclusions or more specifically create
   SLD block lists -- was examined.  The efficacy of blocking domains
   based on sampled DNS data, e.g., DITL, was investigated by comparing
   measurements of SLDs within DITL and that of a multi-month root
   NXDOMAIN collection at the A and J roots [BLOCKLISTS].  The findings
   provided insights into SLD-root affinities, SLD temporal query
   patterns and occurrence frequencies that demonstrated the
   ineffectiveness of block listing domains based on sampled DNS data
   such as [DITL].

   Measurements of queries specifying the recursion desired (RD) bit to
   the roots in DITL were quantified to identify the level and nature of
   naive DNS clients and to determine and assess potential impacts that
   could arise from the proposed SLD blocking technique to these naive
   clients [RARDBITS].  A substantial proportion of the root server
   request traffic contained queries with the RD bit specified.  Both in
   absolute and relative terms, requests specifying the RD bit for
   applied-for gTLDs were found to be significantly lower when compared
   to existing TLDs.  The root cause determination of what system or
   mechanism is responsible for generating the queries was inconclusive
   and only speculative explanations of faulty implementations of a DNS
   resolving server were hypothesized.  However, the analysis was also
   not able to identify instances of actual or potential harm resulting
   from these naive clients, suggesting if SLD blocking techniques were
   to be utilized, it is unlikely there would be any negative impact to
   these naive clients.

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3.2.  System Analysis

   Comparison of elements can often help us to understand a system as a
   whole.  A passive study of the DNS traffic in a provisioned domain
   such as "corp.com" may elucidate certain name collision parallels
   [CORPCOM].  Such measurements were presented as a proxy for the
   ".corp" potential new gTLD.  According to the study, significant DNS
   traffic volume was directed at a variety of third-level domains under
   "corp.com".  This prompted a series of questions surrounding how name
   collisions can be identified, as most end-users won't recognize that
   problems may be due to a name collision.  How will users know that
   the problem they are experiencing is a result of a new, colliding
   gTLD?  Will support groups be able to diagnose a name collision event
   from reported symptom(s)?  Will a collision-based security hole be
   detectable?

   These questions, upon which underpinnings rely on communication and
   educational awareness, may find recommendations or parallels from
   other system references during the workshop [JASFRAMEWORK] -- such as
   the postal and telephone system.  Most telephone and postal systems
   have evolved over time, requiring individuals to alter the way they
   address their parcels or place their calls.  Both systems implemented
   their changes in such a way that prior to the change, educational
   material is distributed and communicated and for a period of time and
   after the change, compliance of the previous standard is temporarily
   accepted.  While the telephone and postal system operate in a very
   different way than the DNS, these parallels of "advanced
   notification, education and communication, and a grace period" were
   insightful for how other similar systems transitioned.

3.3.  Frameworks: Modeling, Analysis, and  Mitigation

   Statements from several TLD operators during the conference
   reverberated a theme for the need of improved tooling, education, and
   communication surrounding name collisions.  The delegation of new
   gTLDs is an ongoing event, and there is a clear and immediate need
   for these operators to have visibility to monitor and measure the
   effects of these new gTLD delegations.  A lack of tools, shared data,
   communication, and education surrounding name collisions has
   handicapped operators in their ability to quantitatively measure and
   proactively provide any steps for mitigation of risks.  To this end,
   numerous techniques, frameworks, and models that focused on the
   concepts of analyzing, detecting, and measuring various name
   collision risk factors were presented and reviewed with the hope of
   understanding these underlying concerns and issues ([TECHNIQUES]
   [MODELING] [SEARCHLISTS] [DNSENDUSER] [ENTNETWORK]).

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   Data-driven analysis and mitigation require operators to be versed
   and skilled with data analysis techniques to better understand the
   contextual intent and ownership of DNS queries.  An overview of
   various DNS analysis techniques in which ways of decomposing names,
   measuring temporal distributions between queries, and detecting
   organizational/geographical affinities was presented [TECHNIQUES].
   More-specific techniques were also showcased, such as a systematic
   way of observing and characterizing the impact of search lists within
   root DNS traffic allowing operators to quantify the number of unique
   entities that may be reliant on a particular name space
   [SEARCHLISTS].  While not exhaustive, the techniques presented have
   been proven to elucidate patterns within root DNS traffic data and
   could serve as the potential building blocks of a DNS analysis
   framework.

   Most of the previously published work focused on name collisions has
   produced various quantitative analyses based on observations of
   Internet traffic and data, including DNS queries and web content, in
   which behavior and associated risks have been inferred.  An
   understanding of the inverse of the process by starting with a
   fundamental model of name resolution at the client was proposed as an
   alternative means to define risk [MODELING].  This model
   deconstructed the process of name resolution at the resolver library
   of a client system and formalized a model from which derived metrics
   could be used to define and quantify associated risks.  While the
   model presented is only a piece of the greater name collision puzzle,
   it provides potentially new insights into what may otherwise be
   considered a missing piece.

   Just as important as understanding the root causes of name
   collisions, providing effective mitigation strategies is a critical
   piece of the name collision puzzle.  Mitigation can be achieved from
   both higher levels, such as ICANN, as well as the enterprise level.
   Proposed strategies for mitigating name collisions at both of these
   levels were presented.  While the technical details for each proposed
   strategy varies, underlying dependencies in both strategies require
   operators to monitor and educate/train their users.

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3.4.  Conclusions and Next Steps

   In their concluding statement [NEXTSTEPS], the workshop committee
   stated:

      It occurs to the program committee that the analysis of the
      interactions between the different uses of domain names within
      local or global context is almost a nonexistent topic of research.
      This may have to do with the lack of accessible data, lack of
      theory of root causes, a lack of interest, or a bias in the
      participation of the workshop.  We think that this is evidence
      that this study of the global centrally important technical system
      needs to be ramped up.

   Follow-on commentary [NEXTSTEPS] from the attendees reaffirmed this
   opinion with recurring messages of a need to understand the root
   causes of name collision and the need to overcome shortcomings within
   our shared data collection, monitoring, and analysis of the DNS.

   Many name collision unknowns still exist.  What are the root causes
   of these queries?  What is going on within a recursive name server?
   What vulnerabilities or subtle attack vectors do these new gTLD
   delegations enable?  The limited datasets available to researchers
   and operators are not sufficient to draw baseline measurements for
   these questions, forcing the community to make inferences and rank
   guesses as to what is going on within the DNS.  Using these
   suboptimal data repositories to create solutions such as block lists
   is only dealing with the symptoms of the problem and not addressing
   the root cause.  To properly answer these questions, the community
   needs to address the issue of a shortage of funding and data
   collection/analysis.  Communication and educational outreach programs
   need to be improved in order raise the awareness of impacted parties
   and broaden participation and sharing.

4.  Security Considerations

   Workshop participants discussed security aspects related to root
   cause analysis and mitigation techniques of potential name collision
   events.  As noted in several papers and presentations, security
   concerns may both arise and be addressed with name collision
   mitigation techniques.  Follow-on measurement-based research is
   important to security considerations for name collisions.

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5.  Informative References

   [ADDNOCA]        ICANN, "Addendum To Name Collision Occurrence
                    Assessment", November 2014,
                    <http://newgtlds.icann.org/sites/default/files/
                    agreements/name-collision-assessment-
                    addendum-14nov14-en.htm>.

   [BLOCKLISTS]     Thomas, M., Labrou, Y., and A. Simpson, "The
                    Effectiveness of Block Lists in Preventing
                    Collisions", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [COMMENTARY]     Kaliski, B., "Proceedings of Name Collisions
                    Workshop Available", March 2014,
                    <http://www.circleid.com/posts/20140326_proceedings_
                    of_name_collisions_workshop_available/>.

   [CORPCOM]        Strutt, C., "Looking at corp.com as a proxy for
                    .corp", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [DITL]           Center for Applied Internet Data Analysis, "A Day in
                    the Life of the Internet (DITL)", July 2011,
                    <http://www.caida.org/projects/ditl/>.

   [DNS-OARC]       Mitchell, K., "DNS-OARC", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [DNSENDUSER]     Huston, G., "Measuring DNS Behaviors from the End
                    User Perspective", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [ENTNETWORK]     Hoffman, P., "Name Collision Mitigation for
                    Enterprise Networks", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [IAB2008]        IAB, "The IAB's response to ICANN's solicitation on
                    DNS stability", March 2008,
                    <https://www.iab.org/documents/correspondence-
                    reports-documents/docs2008/2008-03-07-icann-new-
                    gtlds/>.

   [IESCPANEL]      Woolf, S., Koch, P., Kolkman, O., Kumari, W., and J.
                    Levine, "Internet Engineering and Standards
                    Considerations", March 2014,
                    <http://namecollisions.net/program/index.html>.

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   [INTERISLE]      ICANN, "Name Collision in the DNS", Version 1.5,
                    August 2013,
                    <https://www.icann.org/en/about/staff/security/
                    ssr/name-collision-02aug13-en.pdf>.

   [IR2012]         ICANN, "Preliminary Report | Regular Meeting of the
                    ICANN Board", September 2012,
                    <http://www.icann.org/en/groups/
                    board/documents/prelim-report-13sep12-en.htm>.

   [ISTUDY]         ICANN, "Security Studies on the Use of Non-Delegated
                    TLDs, and Dotless Names", May 2013,
                    <https://www.icann.org/en/news/announcements/
                    announcement-28may13-en.htm>.

   [JASBUG]         Common Vulnerabilities and Exposures, "Group Policy
                    Remote Code Execution Vulnerability", CVE-2015-0008,
                    February 2015, <http://www.cve.mitre.org/cgi-bin/
                    cvename.cgi?name=CVE-2015-0008>.

   [JASFRAMEWORK]   Schmidt, J., "Name Collisions Management Framework",
                    March 2014,
                    <http://namecollisions.net/program/index.html>.

   [KEEPEYE]        Schneier, B., "Keeping an Eye on Name Collisions",
                    March 2014,
                    <http://namecollisions.net/program/index.html>.

   [MODELING]       Deccio, C. and D. Wessels, "What's in a Name
                    (Collision): Modeling and Quantifying Collision
                    Potential", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [MRDNC]          ICANN, "Mitigating the Risk of DNS Namespace
                    Collisions: A Study on Namespace Collisions in the
                    Global Internet DNS Namespace and a Framework for
                    Risk Mitigation", February 2014,
                    <https://www.icann.org/en/about/staff/
                    security/ssr/name-collision-
                    mitigation-26feb14-en.pdf>.

   [NCOMF]          ICANN, "ICANN Selects Lead for Development of Name
                    Collision Occurrence Management Framework", November
                    2013, <http://www.icann.org/en/news/announcements/
                    announcement-2-11nov13-en.htm>.

Top      ToC       Page 14 
   [NCOMFINAL]      ICANN, "Name Collision Occurrence Management
                    Framework", July 2014,
                    <https://www.icann.org/en/system/files/files/
                    name-collision-framework-30jul14-en.pdf>.

   [NCRI]           ICANN, "Name Collision Resources & Information",
                    <http://www.icann.org/en/help/name-collision>.

   [NCSLDCIV]       ICANN, "Name Collision SLD Controlled Interruption
                    Variations", September 2014,
                    <http://newgtlds.icann.org/sites/default/files/
                    agreements/name-collision-sld-controlled-
                    interruption-12sep14-en.htm>.

   [NEXTSTEPS]      Kaliski, B., "Workshop Wrap-Up and Next Steps",
                    March 2014,
                    <http://namecollisions.net/program/index.html>.

   [NGCOMP]         ICANN, "New gTLD Collision Risk Mitigation", August
                    2013,
                    <https://www.icann.org/en/about/staff/security/ssr/
                    new-gtld-collision-mitigation-05aug13-en.pdf>.

   [NOCA]           ICANN, "Name Collision Occurrence Assessment",
                    August 2014,
                    <http://newgtlds.icann.org/sites/default/files/
                    agreements/name-collision-
                    assessment-04aug14-en.htm>.

   [RARDBITS]       Reid, J., "Analysing the Use of the RA and RD bits
                    in Queries to Root Servers", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [RFC1591]        Postel, J., "Domain Name System Structure and
                    Delegation", RFC 1591, DOI 10.17487/RFC1591, March
                    1994, <http://www.rfc-editor.org/info/rfc1591>.

   [RFC2606]        Eastlake 3rd, D. and A. Panitz, "Reserved Top Level
                    DNS Names", BCP 32, RFC 2606, DOI 10.17487/RFC2606,
                    June 1999, <http://www.rfc-editor.org/info/rfc2606>.

   [RFC6761]        Cheshire, S. and M. Krochmal, "Special-Use Domain
                    Names", RFC 6761, DOI 10.17487/RFC6761, February
                    2013, <http://www.rfc-editor.org/info/rfc6761>.

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   [RFC7719]        Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
                    Terminology", RFC 7719, DOI 10.17487/RFC7719,
                    December 2015,
                    <http://www.rfc-editor.org/info/rfc7719>.

   [RSSAC]          Murai, J., "RSSAC response to the root scaling
                    report", November 2010,
                    <http://www.icann.org/en/news/
                    correspondence/murai-to-board-25nov10-en.pdf>.

   [RSSAC002]       ICANN Root Server System Advisory Committee,
                    "Advisory on Measurements of the Root Server
                    System", November 2014,
                    <https://www.icann.org/en/system/files/files/
                    rssac-002-measurements-root-20nov14-en.pdf>.

   [SAC045]         ICANN Security and Stability Advisory Committee,
                    "Invalid Top Level Domain Queries at the Root Level
                    of the Domain Name System", SAC 045, November 2010,
                    <https://www.icann.org/en/groups/ssac/documents/
                    sac-045-en.pdf>.

   [SAC046]         ICANN Security and Stability Advisory Committee,
                    "Report of the Security and Stability Advisory
                    Committee on Root Scaling", SAC 046, December 2010,
                    <https://www.icann.org/en/groups/ssac/documents/
                    sac-046-en.pdf>.

   [SAC057]         ICANN Security and Stability Advisory Committee,
                    "SSAC Advisory on Internal Name Certificates",
                    SAC057, March 2013,
                    <http://www.icann.org/en/groups/ssac/documents/
                    sac-057-en.pdf>.

   [SEARCHLISTS]    Simpson, A., "Detecting Search Lists in
                    Authoritative DNS", March 2014,
                    <http://namecollisions.net/program/index.html>.

   [TECHNIQUES]     Thomas, M. and A. Simpson, "Analysis Techniques for
                    Determining Cause and Ownership of DNS Queries",
                    March 2014,
                    <http://namecollisions.net/program/index.html>.

   [WPNC]           Verisign, "Workshop and Prize on Root Causes and
                    Mitigation of Name Collisions (WPNC)", June 2014,
                    <http://namecollisions.net/>.

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Appendix A.  Program Committee

   This workshop program committee consisted of Geoff Huston, Burt
   Kaliski, Olaf Kolkman, John Levine, Allison Mankin, Lixia Zhang,
   Anne-Marie Eklund Loewinder, and Andrew Sullivan.

Appendix B.  Workshop Material

   Main Workshop Page: <http://namecollisions.net/>

   Name Collision Invited and Submitted Papers, Panels, and Videos:
   <http://namecollisions.net/program/index.html>

   The peer-reviewed papers were:

   o  "Analysis Techniques for Determining Cause and Ownership of DNS
      Queries" [TECHNIQUES],

   o  "Analysing the Use of the RA and RD bits in Queries to Root
      Servers" [RARDBITS],

   o  "The Effectiveness of Block Lists in Preventing Collisions"
      [BLOCKLISTS],

   o  "What's in a Name (Collision): Modeling and Quantifying Collision
      Potential" [MODELING], and

   o  "Detecting Search Lists in Authoritative DNS" [SEARCHLISTS].

   The invited talks were:

   o  "Keeping an Eye on Name Collisions" [KEEPEYE],

   o  "Looking at corp.com as a proxy for .corp" [CORPCOM],

   o  "Measuring DNS Behaviors from the End User Perspective"
      [DNSENDUSER],

   o  "DNS-OARC" [DNS-OARC], and

   o  "Name Collision Mitigation for Enterprise Networks" [ENTNETWORK].

   The panels and discussions were:

   o  "Internet Engineering and Standards Considerations" [IESCPANEL],

   o  "Name Collisions Management Framework" [JASFRAMEWORK], and

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   o  "Workshop Wrap-Up and Next Steps" [NEXTSTEPS].

Appendix C.  Workshop Participants

   A list of workshop participants is provided at [WPNC].

Acknowledgments

   We would like to thank both the program committee (Appendix A) and
   the workshop participants (Appendix C), with equal appreciation to
   those who spoke formally and those who joined in the lively
   discussions.

   Additionally, we would like to thank the following people for their
   review comments: Burt Kaliski, Olaf Kolkman, Ed Lewis, Nevil
   Brownlee, Tim Wicinski, and Danny McPherson.

Authors' Addresses

   Matthew Thomas
   Email: mthomas@verisign.com

   Allison Mankin
   Salesforce
   Email: allison.mankin@gmail.com

   Lixia Zhang
   UCLA
   Email: lixia@cs.ucla.edu