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DNSEXT Working Group                                            E. Lewis
INTERNET DRAFT                                                   NeuStar
Expiration Date: August 10, 2005                           February 2005

                       The Role of Wildcard Domains
                        in the Domain Name System

                  draft-ietf-dnsext-wcard-clarify-05.txt

Status of this Memo

    By submitting this Internet-Draft, each author represents that any
    applicable patent or other IPR claims of which he or she is aware
    have been or will be disclosed, and any of which he or she becomes
    aware will be disclosed, in accordance with Section 6 of RFC 3668.

    Internet-Drafts are working documents of the Internet Engineering
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    This Internet-Draft will expire on August 10, 2005.

Copyright Notice

    Copyright (C) The Internet Society (2005).

Abstract

    This is an update to the wildcard definition of RFC 1034.  The
    interaction with wildcards and CNAME is changed, an error
    condition removed, and the words defining some concepts central to
    wildcards are changed.  The overall goal is not to change wildcards,
    but to refine the definition of RFC 1034.

1 Introduction

    In RFC 1034 [RFC1034], sections 4.3.2 and 4.3.3 describe the synthesis
    of answers from special resource records called wildcards.  The definition
    in RFC 1034 is incomplete and has proven to be confusing.  This document
    describes the wildcard synthesis by adding to the discussion and making
    limited modifications.  Modifications are made to close inconsistencies
    that have led to interoperability issues.  This description does not
    expand the service intended by the original definition.

    Staying within the spirit and style of the original documents, this
    document avoids specifying rules for DNS implementations regarding
    wildcards.  The intention is to only describe what is needed for
    interoperability, not restrict implementation choices.  In addition,
    consideration has been given to minimize any backwards compatibility
    with implementations that have complied with RFC 1034's definition.

    This document is focused on the concept of wildcards as defined in RFC
    1034.  Nothing is implied regarding alternative approaches, nor are
    alternatives discussed.

    [Note to the WG - this draft is not complete, it is presented as fodder
    for the upcoming meeting.  Sections 4.2.3, 4.6, 3.7, and 4.8 are
    particularly incomplete.  I wanted to make sure there was something
    recent in the draft repository before setting out on more travel.

    For 4.2.3, refer to the threads for the most recent discussions...
    http://ops.ietf.org/lists/namedroppers/namedroppers.2004/msg01601.html
    http://ops.ietf.org/lists/namedroppers/namedroppers.2004/msg01603.html

    And you might want to check out the minutes from the last IETF meeting
    as well as http://www.ietf.org/proceedings/03nov/131.htm.]

1.1 Motivation

    Many DNS implementations have diverged with respect to wildcards in
    different ways from the original definition, or at from least what
    had been intended.  Although there is clearly a need to clarify the
    original documents in light of this alone, the impetus for this document
    lay in the engineering of the DNS security extensions [RFC TBD].  With
    an unclear definition of wildcards the design of authenticated denial
    became entangled.

    This document is intended to limit changes,  only those based on
    implementation experience, and to remain as close to the original
    document as possible.  To reinforce this, relevant sections of RFC
    1034 are repeated verbatim to help compare the old and new text.

1.2 The Original Definition

    The context of the wildcard concept involves the algorithm by which
    a name server prepares a response (in RFC 1034's section 4.3.2) and
    the way in which a resource record (set) is identified as being a
    source of synthetic data (section 4.3.3).

    The beginning of the discussion ought to start with the definition
    of the term "wildcard" as it appears in RFC 1034, section 4.3.3.

# In the previous algorithm, special treatment was given to RRs with owner
# names starting with the label "*".  Such RRs are called wildcards.
# Wildcard RRs can be thought of as instructions for synthesizing RRs.
# When the appropriate conditions are met, the name server creates RRs
# with an owner name equal to the query name and contents taken from the
# wildcard RRs.

    This passage appears after the algorithm in which the term wildcard
    is first used.   In this definition, wildcard refers to resource
    records.  In other usage, wildcard has referred to domain names, and
    it has been used to describe the operational practice of relying on
    wildcards to generate answers.  It is clear from this that there is
    a need to define clear and unambiguous terminology in the process of
    discussing wildcards.

    The mention of the use of wildcards in the preparation of a response
    is contained in step 3c of RFC 1034's section 4.3.2 entitled "Algorithm."
    Note that "wildcard" does not appear in the algorithm, instead references
    are made to the "*" label.  The portion of the algorithm relating to
    wildcards is deconstructed in detail in section 3 of this document,
    this is the beginning of the passage.

#        c. If at some label, a match is impossible (i.e., the
#           corresponding label does not exist), look to see if a
#           the "*" label exists.

    The scope of this document is the RFC 1034 definition of wildcards and
    the implications of updates to those documents, such as DNSSEC.  Alternate
    schemes for synthesizing answers are not considered.  (Note that there
    is no reference listed.  No document is known to describe any alternate
    schemes, although there has been some mention of them in mailing lists.)

1.3 This Document

    This document accomplishes these three items.
    o Defines new terms
    o Makes minor changes to avoid conflicting concepts
    o Describe the actions of certain resource records as wildcards

1.3.1 New Terms

    To help in discussing what resource records are wildcards, two terms
    will be defined - "asterisk label" and "wild card domain name".  These
    are defined in section 2.1.1.

    To assist in clarifying the role of wildcards in the name server algorithm
    in RFC 1034, 4.3.2, "source of synthesis" and "closest encloser" are
    defined.  These definitions are in section 3.3.2.  "Label match" is
    defined in section 3.2.

    The introduction of new terms ought not have an impact on any existing
    implementations.  The new terms are used only to make discussions of
    wildcards clearer.

1.3.2 Changed Text

    The definition of "existence" is changed, superficially.  This
    change will not be apparent to implementations; it is needed to
    make descriptions more precise.  The change appears in section 2.2.3.

    RFC 1034, section 4.3.3., seems to prohibit having two asterisk
    labels in a wildcard owner name.  With this document the restriction
    is removed entirely.  This change and its implications are in
    section 2.1.3.

    The actions when a source of synthesis owns a CNAME RR are changed to
    mirror the actions if an exact match name owns a CNAME RR.  This
    is an addition to the words in RFC 1034, section 4.3.2, step 3,
    part c.  The discussion of this is in section 3.3.3.

    Only the latter change represents an impact to implementations.  The
    definition of existence is not a protocol impact.  The change to the
    restriction on names is unlikely to have an impact, as there was no
    discussion of how to enforce the restriction.

1.3.3 Considerations with Special Types

    This document describes semantics of wildcard CNAME RRSets [RFC2181],
    wildcard NS RRSets, wildcard SOA RRSets, wildcard DNAME RRSets
    [RFC2672], wildcard DS RRSets [RFC TBD], and empty non-terminal
    wildcards.  Understanding these types in the context of wildcards
    has been clouded because these types incur special processing if they
    are the result of an exact match.  This discussion is in section 4.

    These discussions do not have an implementation impact, they cover
    existing knowledge of the types, but to a greater level of detail.

1.4 Standards Terminology

    This document does not use terms as defined in "Key words for use in
    RFCs to Indicate Requirement Levels." [RFC2119]

    Quotations of RFC 1034 are denoted by a '#' in the leftmost column.

2 Wildcard Syntax

    The syntax of a wildcard is the same as any other DNS resource record,
    across all classes and types.  The only significant feature is the
    owner name.

    Because wildcards are encoded as resource records with special names,
    they are included in zone transfers and incremental zone transfers.
    [RFC1995].  This feature has been underappreciated until discussions
    on alternative approaches to wildcards appeared on mailing lists.

2.1 Identifying a wildcard

    To provide a more accurate description of "wildcards", the definition
    has to start with a discussion of the domain names that appear as
    owners.  Two new terms are needed, "Asterisk Label" and "Wild Card
    Domain Name."

2.1.1 Wild Card Domain Name and Asterisk Label

    A "wild card domain name" is defined by having its initial
    (i.e., left-most or least significant) label be, in binary format:

         0000 0001 0010 1010 (binary) = 0x01 0x2a (hexadecimal)

    The first octet is the normal label type and length for a 1 octet
    long label, the second octet is the ASCII representation [RFC20] for
    the '*' character.

    A descriptive name of a label equaling that value is an "asterisk
    label."

    RFC 1034's definition of wildcard would be "a resource record owned
    by a wild card domain name."

2.1.2 Asterisks and Other Characters

    No label values other than that in section 2.1.1 are asterisk labels,
    hence names beginning with other labels are never wild card domain
    names.  Labels such as 'the*' and '**' are not asterisk labels,
    they do not start wild card domain names.

2.1.3 Non-terminal Wild Card Domain Names

    In section 4.3.3, the following is stated:

#   ..........................  The owner name of the wildcard RRs is of
#   the form "*.<anydomain>", where <anydomain> is any domain name.
#   <anydomain> should not contain other * labels......................

    This restriction is lifted because the original documentation of it
    is incomplete and the restriction does not serve any purpose given
    years of operational experience.

    Indirectly, the above passage raises questions about wild card domain
    names having subdomains and possibly being an empty non-terminal.  By
    thinking of domain names such as "*.example.*.example." and
    "*.*.example." and focusing on the right-most asterisk label in each,
    the issues become apparent.

    Although those example names have been restricted per RFC 1034, a name
    such as "example.*.example." illustrates the same problems.  The
    sticky issue of subdomains and empty non-terminals is not removed by
    the restriction.  With that conclusion, the restriction appears to
    be meaningless, worse yet, it implies that an implementation would have
    to perform checks that do little more than waste CPU cycles.

    A wild card domain name can have subdomains.  There is no need to
    inspect the subdomains to see if there is another asterisk label in
    any subdomain.

    A wild card domain name can be an empty non-terminal.  (See the upcoming
    sections on empty non-terminals.)  In this case, any lookup encountering
    it will terminate as would any empty non-terminal match.

2.2 Existence Rules

    The notion that a domain name 'exists' is mentioned in the definition
    of wildcards.  In section 4.3.3 of RFC 1034:

# Wildcard RRs do not apply:
#
...
#   - When the query name or a name between the wildcard domain and
#     the query name is know[n] to exist.  For example, if a wildcard

    RFC 1034 also refers to non-existence in the process of generating
    a response that results in a return code of "name error."  NXDOMAIN
    is introduced in RFC 2308, section 2.1 says "In this case the domain
    ... does not exist." The overloading of the term "existence" is
    confusing.

    For the purposes of this document, a domain name is said to exist if
    it plays a role in the execution of the algorithms in RFC 1034.  This
    document avoids discussion determining when an authoritative name
    error has occurred.

2.2.1 An Example

    To illustrate what is meant by existence consider this complete zone:

            $ORIGIN example.
            example.                  3600 IN  SOA   <SOA RDATA>
            example.                  3600     NS    ns.example.com.
            example.                  3600     NS    ns.example.net.
            *.example.                3600     TXT   "this is a wild card"
            *.example.                3600     MX    10 host1.example.
            sub.*.example.            3600     TXT   "this is not a wild card"
            host1.example.            3600     A     192.0.4.1
            _ssh._tcp.host1.example.  3600     SRV  <SRV RDATA>
            _ssh._tcp.host2.example.  3600     SRV  <SRV RDATA>
            subdel.example.           3600     NS   ns.example.com.
            subdel.example.           3600     NS   ns.example.net.

    A look at the domain names in a tree structure is helpful:

                                  |
                  -------------example------------
                 /           /         \          \
                /           /           \          \
               /           /             \          \
              *          host1          host2      subdel
              |            |             |
              |            |             |
             sub         _tcp          _tcp
                           |             |
                           |             |
                         _ssh          _ssh

    The following queries would be synthesized from one of the wildcards:

         QNAME=host3.example. QTYPE=MX, QCLASS=IN
              the answer will be a "host3.example. IN MX ..."

         QNAME=host3.example. QTYPE=A, QCLASS=IN
              the answer will reflect "no error, but no data"
              because there is no A RR set at '*.example.'

         QNAME=foo.bar.example. QTYPE=TXT, QCLASS=IN
              the answer will be "foo.bar.example. IN TXT ..."
              because bar.example. does not exist, but the wildcard does.

    The following queries would not be synthesized from any of the wildcards:

         QNAME=host1.example., QTYPE=MX, QCLASS=IN
              because host1.example. exists

         QNAME=ghost.*.example., QTYPE=MX, QCLASS=IN
              because *.example. exists

         QNAME=sub.*.example., QTYPE=MX, QCLASS=IN
              because sub.*.example. exists

         QNAME=_telnet._tcp.host1.example., QTYPE=SRV, QCLASS=IN
              because _tcp.host1.example. exists (without data)

         QNAME=host.subdel.example., QTYPE=A, QCLASS=IN
              because subdel.example. exists (and is a zone cut)

2.2.2 Empty Non-terminals

    Empty non-terminals [RFC2136, Section 7.16] are domain names that own
    no resource records but have subdomains that do.  In section 2.2.1,
    "_tcp.host1.example." is an example of a empty non-terminal name.
    Empty non-terminals are introduced by this text in section 3.1 of RFC
    1034:

#    The domain name space is a tree structure.  Each node and leaf on the
#    tree corresponds to a resource set (which may be empty).  The domain
#    system makes no distinctions between the uses of the interior nodes and
#    leaves, and this memo uses the term "node" to refer to both.

    The parenthesized "which may be empty" specifies that empty non-
    terminals are explicitly recognized, and that empty non-terminals
    "exist."

    Pedantically reading the above paragraph can lead to an
    interpretation that all possible domains exist - up to the suggested
    limit of 255 octets for a domain name [RFC1035].  For example,
    www.example. may have an A RR, and as far as is practically
    concerned, is a leaf of the domain tree.  But the definition can be
    taken to mean that sub.www.example. also exists, albeit with no data.
    By extension, all possible domains exist, from the root on down.  As
    RFC 1034 also defines "an authoritative name error indicating that
    the name does not exist" in section 4.3.1, this is not the intent of
    the original document.

2.2.3 Yet Another Definition of Existence

    RFC1034's wording is fixed by the following paragraph:

    The domain name space is a tree structure.  Nodes in the tree either
    own at least one RRSet and/or have descendants that collectively own at
    least on RRSet.  A node may have no RRSets if it has descendents that
    do, this node is a empty non-terminal.  A node may have its own RRSets
    and have descendants with RRSets too.

    A node with no descendants is a leaf node.  Empty leaf nodes do not
    exist.

    Note that at a zone boundary, the domain name owns data, including
    the NS RR set.  At the delegating server, the NS RR set is not
    authoritative, but that is of no consequence here.  The domain name
    owns data, therefore, it exists.

2.3 When does a Wild Card Domain Name is not Special

    When a wild card domain name appears in a message's query section,
    no special processing occurs.  An asterisk label in a query name
    only (label) matches an asterisk label in the existing zone tree
    when the 4.3.2 algorithm is being followed.

    When a wild card domain name appears in the resource data of a
    record, no special processing occurs.  An asterisk label in that
    context literally means just an asterisk.

3. Impact of a Wild Card Domain Name On a Response

    The description of how wildcards impact response generation is in
    RFC 1034, section 4.3.2.  That passage contains the algorithm
    followed by a server in constructing a response.  Within that
    algorithm, step 3, part 'c' defines the behavior of the wild card.

    The algorithm in RFC 1034, section 4.3.2. is not intended to be pseudo
    code, i.e., its steps are not intended to be followed in strict
    order.  The "algorithm" is a suggestion.  As such, in step 3, parts
    a, b, and c, do not have to be implemented in that order.

3.1 Step 2

    Step 2 of the RFC 1034's section 4.3.2 reads:

#   2. Search the available zones for the zone which is the nearest
#      ancestor to QNAME.  If such a zone is found, go to step 3,
#      otherwise step 4.

    In this step, the most appropriate zone for the response is chosen.
    The significance of this step is that it means all of step 3 is being
    performed within one zone.  This has significance when considering
    whether or not an SOA RR can be ever be used for synthesis.

3.2 Step 3

    Step 3 is dominated by three parts, labelled 'a', 'b', and 'c'.  But the
    beginning of the step is important and needs explanation.

#   3. Start matching down, label by label, in the zone.  The
#      matching process can terminate several ways:

    The word 'matching' refers to label matching.  The concept
    is based in the view of the zone as the tree of existing names.  The
    query name is considered to be an ordered sequence of labels - as
    if the name were a path from the root to the owner of the desired
    data.  (Which it is - 3rd paragraph of RFC 1034, section 3.1.)

    The process of label matching  a query name ends in exactly one of three
    choices, the parts 'a', 'b', and 'c'.  Either the name is found, the
    name is below a cut point, or the name is not found.

    Once one of the parts is chosen, the other parts are not considered.
    (E.g., do not execute part 'c' and then change the execution path to
    finish in part 'b'.)  The process of label matching is also done
    independent of the query type (QTYPE).

    Parts 'a' and 'b' are not an issue for this clarification as they do not
    relate to record synthesis.  Part 'a' is an exact match that results in
    an answer, part 'b' is a referral.  It is possible, from the description
    given, that a query might fit into both part a and part b, this is
    not within the scope of this document.

3.3 Part 'c'

    The context of part 'c' is that the process of label matching the
    labels of the query name has resulted in a situation in which there
    is no corresponding label in the tree.  It is as if the lookup has
    "fallen off the tree."

#         c. If at some label, a match is impossible (i.e., the
#            corresponding label does not exist), look to see if a
#            the "*" label exists.


    To help describe the process of looking 'to see if a [sic] the "*"
    label exists' a term has been coined to describe the last label
    matched.  The term is "closest encloser."

3.3.1 Closest Encloser and the Source of Synthesis

    The closest encloser is the node in the zone's tree of existing
    domain names that has the most labels matching the query name
    (consecutively, counting from the root label downward). Each match
    is a "label match" and the order of the labels is the same.

    The closest encloser is, by definition, an existing name in the zone.  The
    closest encloser might be an empty non-terminal or even be a wild card
    domain name itself.  In no circumstances is the closest encloser
    the used to synthesize records for the current query.

    The source of synthesis is defined in the context of a query process
    as that wild card domain name immediately descending from the
    closest encloser, provided that this wild card domain name exists.
    "Immediately descending" means that the source of synthesis has a name
    of the form <asterisk label>.<closest encloser>.  A source of synthesis
    does not guarantee having a RRSet to use for synthesis.  The source of
    synthesis could be an empty non-terminal.

    If the source of synthesis does not exist (not on the domain tree),
    there will be no wildcard synthesis.  There is no search for an alternate.

    The important concept is that for any given lookup process, there
    is at most one place at which wildcard synthetic records can be
    obtained.  If the source of synthesis does not exist, the lookup
    terminates, the lookup does not look for other wildcard records.

3.3.2 Closest Encloser and Source of Synthesis Examples

    To illustrate, using the example zone in section 2.2.1 of this document,
    the following chart shows QNAMEs and the closest enclosers.

     QNAME                        Closest Encloser     Source of Synthesis
     host3.example.               example.             *.example.
     _telnet._tcp.host1.example.  _tcp.host1.example.  no source
     _telnet._tcp.host2.example.  host2.example.       no source
     _telnet._tcp.host3.example.  example.             *.example.
     _chat._udp.host3.example.    example.             *.example.
     foobar.*.example.            *.example.           no source

3.3.3 Type Matching

     RFC 1034 concludes part 'c' with this:

#            If the "*" label does not exist, check whether the name
#            we are looking for is the original QNAME in the query
#            or a name we have followed due to a CNAME.  If the name
#            is original, set an authoritative name error in the
#            response and exit.  Otherwise just exit.
#
#            If the "*" label does exist, match RRs at that node
#            against QTYPE.  If any match, copy them into the answer
#            section, but set the owner of the RR to be QNAME, and
#            not the node with the "*" label.  Go to step 6.

    The final paragraph covers the role of the QTYPE in the lookup process.

    Based on implementation feedback and similarities between step 'a' and
    step 'c' a change to this passage a change has been made.

    The change is to add the following text to step 'c':

             If the data at the source of synthesis is a CNAME, and
             QTYPE doesn't match CNAME, copy the CNAME RR into the
             answer section of the response changing the owner name
             to the QNAME, change QNAME to the canonical name in the
             CNAME RR, and go back to step 1.

    This is essentially the same text in step a covering the processing of
    CNAME RRSets.

4. Considerations with Special Types

    Sections 2 and 3 of this document discuss wildcard synthesis with
    respect to names in the domain tree and ignore the impact of types.
    In this section, the implication of wildcards of specific types are
    discussed.  The types covered are those that have proven to be the
    most difficult to understand.  The types are SOA, NS, CNAME, DNAME,
    SRV, DS, NSEC, RRSIG and "none," i.e., empty non-terminal wild card
    domain names.

4.1 SOA RRSet at a Wild Card Domain Name

    A wild card domain name owning an SOA RRSet means that the domain
    is at the root of the zone (apex).  The domain can not be a source of
    synthesis because that is, by definition, a descendent node (of
    the closest encloser) and a zone apex is at the top of the zone.

    Although a wild card domain name owning an SOA RRSet can never be a
    source of synthesis, there is no reason to forbid the ownership of
    an SOA RRSet.

    E.g., given this zone:
           $ORIGIN *.example.
           @                 3600 IN  SOA   <SOA RDATA>
                             3600     NS    ns1.example.com.
                             3600     NS    ns1.example.net.
           www               3600     TXT   "the www txt record"

    A query for www.*.example.'s TXT record would still find the "the www txt
    record" answer.  The reason is that the asterisk label only becomes
    significant when RFC 1034's 4.3.2, step 3 part 'c' in in effect.

    Of course, there would need to be a delegation in the parent zone,
    "example." for this to work too.  This is covered in the next section.

4.2 NS RRSet at a Wild Card Domain Name

    The semantics of a wild card domain name's ownership of a NS RRSet
    has been unclear.  There are three considerations to cover.  One is
    is that if the query processing lands in part 'a' or part 'b' of
    RFC 1034's 4.3.2, step 3, the incidence of the wild card domain name
    owning an NS RRset has no special meaning.  Second, synthesized
    records never appear in the authority section of a response, meaning
    that referrals are never synthesized.  And finally, DNSSEC validators
    will have to be aware of a quirk in ownership rules.

4.2.1 NS, *, and answers

    If the NS RRSet in question is at the top of the zone, i.e., the
    name also owns an SOA RRSet, the QNAME equals the zone name.  This
    would trigger part 'a' of step 3.

4.2.2 NS, *, and referrals

    If the NS RRset is not at the top of the zone and part 'b' is triggered,
    this implies that the labels being matched are an asterisk label in
    the QNAME and the asterisk label owning the NS RRset.  In either case,
    what is copied to the response will have the asterisk label in it - no
    synthesis, no name substitution.

    E.g., consider the parent zone for the example in section 4.1.
           $ORIGIN example.
           @                 3600 IN  SOA   <SOA RDATA>
                             3600     NS    ns0.example.com.
                             3600     NS    ns0.example.net.
           *                 3600     NS    ns1.example.com.
                             3600     NS    ns1.example.net.

    If the query for www.*.example.'s TXT set arrived here, the response
    would be a referral as in part 'b'.

           Response, non-authoritative, no error rcode
           ANSWER: (empty)
           AUTHORITY:
           *                 3600     NS    ns1.example.com.
                             3600     NS    ns1.example.net.
           ADDITIIONAL: (empty, or with OPT RR)

    The same response message would be sent to a query for *.example.'s NS
    set.  Note that the NS records in the response are not expanded, simply
    copied verbatim.  (Compare this the case where "*" is "star".)

    There is no synthesis of records in the authority section because part
    'b' does not specify synthesis.  The referral returned would have the
    wild card domain name in the authority section unchanged.

4.2.3 NS, *, and synthesis

    If the QNAME is not the same as the wild card domain name nor a
    subdomain of it, then part 'c' of step 3 has been triggered.  Assuming
    that "a match is impossible" a source of synthesis is sought.  If
    the source of synthesis owns an NS RRset and the QTYPE is NS, then
    a NS RRset is synthesized and put into the answer section and marked
    as an authoritative answer.  If the QTYPE is not NS, then the NS RRset
    is ignored, as it would have been if it were an A RR and the QTYPE was
    AAAA.  An NS RRSet at a wild card domain name will not result in
    the generation of referral messages for non-existent domains because
    part 'c' does not write anything into the authority section.

   (If we choose this, then we have to have a section 4.2.4 on DNSSEC
   implications.)

OR

    If the QNAME is not the same as the wild card domain name nor a
    subdomain of it, then part 'c' of step 3 has been triggered.  Assuming
    that "a match is impossible" a source of synthesis is sought.  If
    the source of synthesis owns an NS RRset and the QTYPE is NS, then
    no synthesis happens.  A NS RRset is never synthesized.  The proper
    response is, what, no error/no data? Name error?

OR

    If the QNAME is not the same as the wild card domain name nor a
    subdomain of it, then part 'c' of step 3 has been triggered.  Assuming
    that "a match is impossible" a source of synthesis is sought.  If
    the source of synthesis owns an NS RRset then no synthesis happens.
    A cut point is never a source of synthesis.  The proper response is,
    what, no error/no data? Name error?

4.3 CNAME RRSet at a Wild Card Domain Name

    The issue of a CNAME RRSet owned by wild card domain names has prompted
    a suggested change to the last paragraph of step 3c of the algorithm
    in 4.3.2.  The changed text appears in section 3.3.3 of this document.

4.4 DNAME RRSet at a Wild Card Domain Name

    A DNAME RRset at a wild card domain name is effectively the same
    as a CNAME at a wild card domain name.

4.5 SRV RRSet at a Wild Card Domain Name

    The definition of the SRV RRset is RFC 2782 [RFC2782].  In the
    definition of the record, there is some confusion over the term
    "Name."  The definition reads as follows:

# The format of the SRV RR
...
#        _Service._Proto.Name TTL Class SRV Priority Weight Port Target
...
#   Name
#        The domain this RR refers to.  The SRV RR is unique in that the
#        name one searches for is not this name; the example near the end
#        shows this clearly.

     Do not confuse the definition "Name" with a domain name.  I.e., once
     removing the _Service and _Proto labels from the owner name of the
     SRV RRSet, what remains could be a wild card domain name but this is
     immaterial to the SRV RRSet.

     E.g.,  If an SRV record is:
          _foo._udp.*.example. 10800 IN SRV 0 1 9 old-slow-box.example.

     *.example is a wild card domain name and although it it the Name of
     the SRV RR, it is not the owner (domain name).  The owner domain name
     is "_foo._udp.*.example." which is not a wild card domain name.

     The confusion is likely based on the mixture of the specification of
     the SRV RR and the description of a "use case."

4.6 DS RRSet at a Wild Card Domain Name

...probably harmless...

4.7 NSEC RRSet at a Wild Card Domain Name

...will be present, don't know if it should be synthesized...

4.8 RRSIG at a Wild Card Domain Name

...need to cross check with DNSSECbis to see what is said about querying
for RRSIG...

4.9 Empty Non-terminal Wild Card Domain Name

    If a source of synthesis is an empty non-terminal, then the response
    will be one of no error in the return code and no RRSet in the answer
    section.

5. Security Considerations

    This document is refining the specifications to make it more likely
    that security can be added to DNS.  No functional additions are being
    made, just refining what is considered proper to allow the DNS,
    security of the DNS, and extending the DNS to be more predictable.

6. References

    Normative References

    [RFC20] ASCII Format for Network Interchange, V.G. Cerf, Oct-16-1969

    [RFC1034] Domain Names - Concepts and Facilities, P.V. Mockapetris,
               Nov-01-1987

    [RFC1035] Domain Names - Implementation and Specification, P.V
               Mockapetris, Nov-01-1987

    [RFC1995] IXFR ... Ohta

    [RFC2119] Key Words for Use in RFCs to Indicate Requirement Levels, S
               Bradner, March 1997

    [RFC2181] Clarifications to the DNS Specification, R. Elz and R. Bush,
               July 1997.

    [RFC2782] A DNS RR for specifying the location of services (DNS SRV),
               A. Gulbrandsen, et.al., February 2000.

    Informative References

    [RFC2136] Dynamic Updates in the Domain Name System (DNS UPDATE), P.
               Vixie, Ed., S. Thomson, Y. Rekhter, J. Bound, April 1997

    [RFC2535] Domain Name System Security Extensions, D. Eastlake, March 1999

    [RFC2672] Non-Terminal DNS Name Redirection, M. Crawford, August 1999

7. Others Contributing to This Document

    Others who have been editors of this document: Bob Halley.
    Others who have directly caused text to appear in the document: Alex
    Bligh, Robert Elz, Paul Vixie, David Blacka and Olaf Kolkman.
    Many others have indirect influences on the content.

8. Editor

         Name:         Edward Lewis
         Affiliation:  NeuStar
         Address:      46000 Center Oak Plaza, Sterling, VA, 20166, US
         Phone:        +1-571-434-5468
         Email:        ed.lewis@neustar.biz

    Comments on this document can be sent to the editor or the mailing
    list for the DNSEXT WG, namedroppers@ops.ietf.org.

9. Trailing Boilerplate

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    to the rights, licenses and restrictions contained in BCP 78 and
    except as set forth therein, the authors retain all their rights.

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Expiration

    This document expires on or about August 10, 2005.


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