INTERNET-DRAFT                                       Donald Eastlake 3rd
Obsoletes: 5395                                         Stellar Switches
Updates: 1183, 3597
Intended status: Best Current Practice
Expires: May 10, 25, 2011                                  November 11, 26, 2010

              Domain Name System (DNS) IANA Considerations


   Internet Assigned Number Authority (IANA) parameter assignment
   considerations are specified for the allocation of Domain Name System
   (DNS) resource record types, CLASSes, operation codes, error codes,
   DNS protocol message header bits, and AFSDB resource record subtypes.

Status of This Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Distribution of this draft is unlimited. It is intended to become the
   new BCP 42 obsoleting RFC 5395. Comments should be sent to the DNS
   Extensions Working Group mailing list <>.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at

   The list of Internet-Draft Shadow Directories can be accessed at

Table of Contents

      1. Introduction............................................3
      1.1. Terminology...........................................3

      2. DNS Query/Response Headers..............................4
      2.1. One Spare Bit?........................................4
      2.2. OpCode Assignment.....................................5
      2.3. RCODE Assignment......................................5

      3. DNS Resource Records....................................7
      3.1. RRTYPE IANA Considerations............................8
      3.1.1. DNS RRTYPE Allocation Policy........................9
      3.1.2. DNS RRTYPE Expert Guidelines.......................10
      3.1.3. Special Note on the OPT RR.........................10
      3.1.4. The AFSDB RR Subtype Field.........................10
      3.2. RR CLASS IANA Considerations.........................11
      3.3. Label Considerations.................................13
      3.3.1. Label Types........................................13
      3.3.2. Label Contents and Use.............................13

      4. Security Considerations................................14
      5. IANA Considerations....................................14

      Annex A: RRTYPE Allocation Template.......................15
      Annex B: Changes From RFC 5395............................17

      Normative References......................................18
      Informative References....................................19

1. Introduction

   The Domain Name System (DNS) provides replicated distributed secure
   hierarchical databases that store "resource records" (RRs) under
   domain names. DNS data is structured into CLASSes and zones that can
   be independently maintained. See [RFC1034], [RFC1035], [RFC2136],
   [RFC2181], and [RFC4033], familiarity with which is assumed.

   This document provides, either directly or by reference, the general
   IANA parameter assignment considerations that apply across DNS query
   and response headers and all RRs. There may be additional IANA
   considerations that apply to only a particular RRTYPE or
   query/response OpCode. See the specific RFC defining that RRTYPE or
   query/response OpCode for such considerations if they have been
   defined, except for AFSDB RR considerations [RFC1183], which are
   included herein. This RFC obsoletes [RFC5395]; however, the only
   significant change is the change is the public review mailing list to

   IANA currently maintains a web page of DNS parameters available from

1.1. Terminology

   "IETF Standards Action", "IETF Review", "Specification Required", and
   "Private Use" are as defined in [RFC5226].

2. DNS Query/Response Headers

   The header for DNS queries and responses contains field/bits in the
   following diagram taken from [RFC2136] and [RFC5395]:

                                              1  1  1  1  1  1
                0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
               |                      ID                       |
               |QR|   OpCode  |AA|TC|RD|RA| Z|AD|CD|   RCODE   |
               |                QDCOUNT/ZOCOUNT                |
               |                ANCOUNT/PRCOUNT                |
               |                NSCOUNT/UPCOUNT                |
               |                    ARCOUNT                    |

   The ID field identifies the query and is echoed in the response so
   they can be matched.

   The QR bit indicates whether the header is for a query or a response.

   The AA, TC, RD, RA, AD, and CD bits are each theoretically meaningful
   only in queries or only in responses, depending on the bit. However,
   some DNS implementations copy the query header as the initial value
   of the response header without clearing bits. Thus, any attempt to
   use a "query" bit with a different meaning in a response or to define
   a query meaning for a "response" bit is dangerous, given existing
   implementation. Such meanings may only be assigned by an IETF
   Standards Action.

   The unsigned integer fields query count (QDCOUNT), answer count
   (ANCOUNT), authority count (NSCOUNT), and additional information
   count (ARCOUNT) express the number of records in each section for all
   OpCodes except Update [RFC2136]. These fields have the same structure
   and data type for Update but are instead the counts for the zone
   (ZOCOUNT), prerequisite (PRCOUNT), update (UPCOUNT), and additional
   information (ARCOUNT) sections.

2.1. One Spare Bit?

   There have been ancient DNS implementations for which the Z bit being
   on in a query meant that only a response from the primary server for
   a zone is acceptable. It is believed that current DNS implementations
   ignore this bit.

   Assigning a meaning to the Z bit requires an IETF Standards Action.

2.2. OpCode Assignment

   Currently DNS OpCodes are assigned as follows:

          OpCode Name                      Reference

           0     Query                     [RFC1035]
           1     IQuery  (Inverse Query, Obsolete) [RFC3425]
           2     Status                    [RFC1035]
           3     available for assignment
           4     Notify                    [RFC1996]
           5     Update                    [RFC2136]
          6-15   available for assignment

   New OpCode assignments require an IETF Standards Action as modified
   by [RFC4020].

2.3. RCODE Assignment

   It would appear from the DNS header above that only four bits of
   RCODE, or response/error code, are available. However, RCODEs can
   appear not only at the top level of a DNS response but also inside
   OPT RRs [RFC2671], TSIG RRs [RFC2845], and TKEY RRs [RFC2930]. The
   OPT RR provides an 8-bit extension resulting in a 12-bit RCODE field,
   and the TSIG and TKEY RRs have a 16-bit RCODE field.

   Error codes appearing in the DNS header and in these three RR types
   all refer to the same error code space with the single exception of
   error code 16 which has a different meaning in the OPT RR from its
   meaning in other contexts. See table below.

        RCODE   Name    Description                        Reference
         0    NoError   No Error                           [RFC1035]
         1    FormErr   Format Error                       [RFC1035]
         2    ServFail  Server Failure                     [RFC1035]
         3    NXDomain  Non-Existent Domain                [RFC1035]
         4    NotImp    Not Implemented                    [RFC1035]
         5    Refused   Query Refused                      [RFC1035]
         6    YXDomain  Name Exists when it should not     [RFC2136]
         7    YXRRSet   RR Set Exists when it should not   [RFC2136]
         8    NXRRSet   RR Set that should exist does not  [RFC2136]
         9    NotAuth   Server Not Authoritative for zone  [RFC2136]
        10    NotZone   Name not contained in zone         [RFC2136]
        11 - 15         Available for assignment
        16    BADVERS   Bad OPT Version                    [RFC2671]
        16    BADSIG    TSIG Signature Failure             [RFC2845]
        17    BADKEY    Key not recognized                 [RFC2845]
        18    BADTIME   Signature out of time window       [RFC2845]
        19    BADMODE   Bad TKEY Mode                      [RFC2930]
        20    BADNAME   Duplicate key name                 [RFC2930]
        21    BADALG    Algorithm not supported            [RFC2930]
        22    BADTRUC   Bad Truncation                     [RFC4635]
        23 - 3,840
    0x0017 - 0x0F00     Available for assignment

     3,841 - 4,095
    0x0F01 - 0x0FFF     Private Use

     4,096 - 65,534
    0x1000 - 0xFFFE     Available for assignment

    0xFFFF              Reserved, can only be allocated by an IETF
                        Standards Action.

   Since it is important that RCODEs be understood for interoperability,
   assignment of new RCODE listed above as "available for assignment"
   requires an IETF Review.

3. DNS Resource Records

   All RRs have the same top-level format, shown in the figure below
   taken from [RFC1035].

                                       1  1  1  1  1  1
         0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
       |                                               |
       /                                               /
       /                      NAME                     /
       /                                               /
       |                      TYPE                     |
       |                     CLASS                     |
       |                      TTL                      |
       |                                               |
       |                   RDLENGTH                    |
       /                     RDATA                     /
       /                                               /

   NAME is an owner name, i.e., the name of the node to which this
   resource record pertains. NAMEs are specific to a CLASS as described
   in section 3.2. NAMEs consist of an ordered sequence of one or more
   labels, each of which has a label type [RFC1035] [RFC2671].

   TYPE is a 2-octet unsigned integer containing one of the RRTYPE
   codes.  See section 3.1.

   CLASS is a 2-octet unsigned integer containing one of the RR CLASS
   codes. See section 3.2.

   TTL is a 4-octet (32-bit) unsigned integer that specifies, for data
   TYPEs, the number of seconds that the resource record may be cached
   before the source of the information should again be consulted. Zero
   is interpreted to mean that the RR can only be used for the
   transaction in progress.

   RDLENGTH is an unsigned 16-bit integer that specifies the length in
   octets of the RDATA field.

   RDATA is a variable length string of octets that constitutes the
   resource. The format of this information varies according to the TYPE
   and, in some cases, the CLASS of the resource record.

3.1. RRTYPE IANA Considerations

   There are three subcategories of RRTYPE numbers: data TYPEs, QTYPEs,
   and Meta-TYPEs.

   Data TYPEs are the means of storing data. QTYPES can only be used in
   queries. Meta-TYPEs designate transient data associated with a
   particular DNS message and, in some cases, can also be used in
   queries.  Thus far, data TYPEs have been assigned from 1 upward plus
   the block from 100 through 103 and from 32,768 upward, while Q and
   Meta-TYPEs have been assigned from 255 downward except for the OPT
   Meta-RR, which is assigned TYPE 41. There have been DNS
   implementations that made caching decisions based on the top bit of
   the bottom byte of the RRTYPE.

   There are currently three Meta-TYPEs assigned: OPT [RFC2671], TSIG
   [RFC2845], and TKEY [RFC2930]. There are currently five QTYPEs
   assigned: * (ALL), MAILA, MAILB, AXFR, and IXFR.

   RRTYPEs have mnemonics that must be completely disjoint from the
   mnemonics used for CLASSes and that must match the following regular


   Considerations for the allocation of new RRTYPEs are as follows:


   0x0000 - RRTYPE zero is used as a special indicator for the SIG (0)
            RR [RFC2931], [RFC4034] and in other circumstances, and it
            must never be allocated for ordinary use.

        1 - 127
   0x0001 - 0x007F - Remaining RRTYPEs in this range are assigned for
            data TYPEs by the DNS RRTYPE Allocation Policy as specified
            in Section 3.1.1.

      128 - 255
   0x0080 - 0x00FF - Remaining RRTYPEs in this range are assigned for Q
            and Meta TYPEs by the DNS RRTYPE Allocation Policy as
            specified in Section 3.1.1.

      256 - 61,439
   0x0100 - 0xEFFF - Remaining RRTYPEs in this range are assigned for
            data RRTYPEs by the DNS RRTYPE Allocation Policy as
            specified in Section 3.1.1. (32,768 and 32,769 (0x8000 and
            0x8001) have been assigned.)

   61,440 - 65,279
   0xF000 - 0xFEFF - Reserved for future use. IETF Review required to
            define use.

   65,280 - 65,534
   0xFF00 - 0xFFFE - Private Use.

   0xFFFF - Reserved, can only be assigned by an IETF Standards Action.

3.1.1. DNS RRTYPE Allocation Policy

   Parameter values specified in Section 3.1 above, as assigned based on
   DNS RRTYPE Allocation Policy, are allocated by Expert Review if they
   meet the two requirements listed below. There will be a pool of a
   small number of Experts appointed by the IESG. Each application will
   be ruled on by an Expert selected by IANA. In any case where the
   selected Expert is unavailable or states they have a conflict of
   interest, IANA may select another Expert from the pool.

   Some guidelines for the Experts are given in Section 3.1.2. RRTYPEs
   that do not meet the requirements below may nonetheless be allocated
   by IETF Standards Action as modified by [RFC4020].

   1. A complete template as specified in Appendix A has been posted for
      three weeks to the mailing list before the Expert
      Review decision.
         Note that partially completed or draft templates may be posted
      directly by the applicant for comment and discussion, but the
      formal posting to start the three week period is made by the

   2. The RR for which an RRTYPE code is being requested is either (a) a
      data TYPE that can be handled as an Unknown RR as described in
      [RFC3597] or (b) a Meta-Type whose processing is optional, i.e.,
      it is safe to simply discard RRs with that Meta-Type in queries or
         Note that such RRs may include additional section processing,
      provided such processing is optional.

   No less than three weeks and no more than six weeks after a completed
   template has been formally posted to, the selected
   Expert shall post a message, explicitly accepting or rejecting the
   application, to IANA,, and the email address provided
   by the applicant. If the Expert does not post such a message, the
   application shall be considered rejected but may be re-submitted to

   IANA shall maintain a public archive of approved templates.

3.1.2. DNS RRTYPE Expert Guidelines

   The selected DNS RRTYPE Expert is required to monitor discussion of
   the proposed RRTYPE, which may occur on the mailing
   list, and may consult with other technical experts as necessary. The
   Expert should normally reject any RRTYPE allocation request that
   meets one or more of the following criterion:

   1. Was documented in a manner that was not sufficiently clear to
      evaluate or implement.

   2. The proposed RRTYPE or RRTYPEs affect DNS processing and do not
      meet the criteria in point 2 of Section 3.1.1 above.

   3. The documentation of the proposed RRTYPE or RRTYPEs is incomplete.
      (Additional documentation can be provided during the public
      comment period or by the Expert.)

   4. Application use as documented makes incorrect assumptions about
      DNS protocol behavior, such as wild cards, CNAME, DNAME, etc.

   5. An excessive number of RRTYPE values is being requested when the
      purpose could be met with a smaller number or with Private Use

3.1.3. Special Note on the OPT RR

   The OPT (OPTion) RR (RRTYPE 41) and its IANA Considerations are
   specified in [RFC2671]. Its primary purpose is to extend the
   effective field size of various DNS fields including RCODE, label
   type, OpCode, flag bits, and RDATA size. In particular, for resolvers
   and servers that recognize it, it extends the RCODE field from 4 to
   12 bits.

3.1.4. The AFSDB RR Subtype Field

   The AFSDB RR [RFC1183] is a CLASS-insensitive RR that has the same
   RDATA field structure as the MX RR, but the 16-bit unsigned integer
   field at the beginning of the RDATA is interpreted as a subtype as


   0x0000 - Reserved; allocation requires IETF Standards Action.

   0x0001 - Andrews File Service v3.0 Location Service [RFC1183].

   0x0002 - DCE/NCA root cell directory node [RFC1183].

        3 - 65,279
   0x0003 - 0xFEFF - Allocation by IETF Review.

   65,280 - 65,534
   0xFF00 - 0xFFFE - Private Use.

   0xFFFF - Reserved; allocation requires IETF Standards Action.

3.2. RR CLASS IANA Considerations

   There are currently two subcategories of DNS CLASSes: normal, data-
   containing classes and QCLASSes that are only meaningful in queries
   or updates.

   DNS CLASSes have been little used but constitute another dimension of
   the DNS distributed database. In particular, there is no necessary
   relationship between the name space or root servers for one data
   CLASS and those for another data CLASS. The same DNS NAME can have
   completely different meanings in different CLASSes. The label types
   are the same, and the null label is usable only as root in every
   CLASS.  As global networking and DNS have evolved, the IN, or
   Internet, CLASS has dominated DNS use.

   As yet there has not be a requirement for "meta-CLASSes". That would
   be a CLASS to designate transient data associated with a particular
   DNS message, which might be usable in queries. However, it is
   possible that there might be a future requirement for one or more

   CLASSes have mnemonics that must be completely disjoint from the
   mnemonics used for RRTYPEs and that must match the following regular


   The current CLASS assignments and considerations for future
   assignments are as follows:


   0x0000 - Reserved; assignment requires an IETF Standards Action.

   0x0001 - Internet (IN).

   0x0002 - Available for assignment by IETF Review as a data CLASS.

   0x0003 - Chaos (CH) [Moon1981].

   0x0004 - Hesiod (HS) [Dyer1987].

        5 - 127
   0x0005 - 0x007F - Available for assignment by IETF Review for data
                     CLASSes only.

      128 - 253
   0x0080 - 0x00FD - Available for assignment by IETF Review for
            QCLASSes and meta-CLASSes only.

   0x00FE - QCLASS NONE [RFC2136].

   0x00FF - QCLASS * (ANY) [RFC1035].

      256 - 32,767
   0x0100 - 0x7FFF - Assigned by IETF Review.

   32,768 - 57,343
   0x8000 - 0xDFFF - Assigned for data CLASSes only, based on
                     Specification Required as defined in [RFC5226].

   57,344 - 65,279
   0xE000 - 0xFEFF - Assigned for QCLASSes and meta-CLASSes only, based
                     on Specification Required as defined in [RFC5226].

   65,280 - 65,534
   0xFF00 - 0xFFFE - Private Use.

   0xFFFF - Reserved; can only be assigned by an IETF Standards Action.

3.3. Label Considerations

   DNS NAMEs are sequences of labels [RFC1035].

3.3.1. Label Types

   At the present time, there are two categories of label types: data
   labels and compression labels. Compression labels are pointers to
   data labels elsewhere within an RR or DNS message and are intended to
   shorten the wire encoding of NAMEs.

   The two existing data label types are sometimes referred to as Text
   and Binary. Text labels can, in fact, include any octet value
   including zero-value octets, but many current uses involve only [US-
   ASCII]. For retrieval, Text labels are defined to treat ASCII upper
   and lower case letter codes as matching [RFC4343]. Binary labels are
   bit sequences [RFC2673]. The Binary label type is Experimental

   IANA considerations for label types are given in [RFC2671].

3.3.2. Label Contents and Use

   The last label in each NAME is "ROOT", which is the zero-length
   label.  By definition, the null or ROOT label cannot be used for any
   other NAME purpose.

   NAMEs are local to a CLASS. The Hesiod [Dyer1987] and Chaos
   [Moon1981] CLASSes are for essentially local use. The IN, or
   Internet, CLASS is thus the only DNS CLASS in global use on the
   Internet at this time.

   A somewhat out-of-date description of name allocation in the IN Class
   is given in [RFC1591]. Some information on reserved top-level domain
   names is in BCP 32 [RFC2606].

4. Security Considerations

   This document addresses IANA considerations in the allocation of
   general DNS parameters, not security. See [RFC4033], [RFC4034], and
   [RFC4035] for secure DNS considerations.

5. IANA Considerations

   This document consists entirely of DNS IANA Considerations.

   IANA shall establish a process for accepting Annex A templates,
   selecting an Expert from those appointed to review such template form
   applications, and archive and make available all approved RRTYPE
   allocation templates. It is the duty of the selected Expert applicant to post the
   formal application template to the dns-rrtype-
   mailing list. See Section 3.1 and Annex A for more details.

Annex A: RRTYPE Allocation Template


   When ready for formal consideration, this template is to be submitted
   to IANA for processing by emailing the template to dns-rrtype-

   A.    Submission Date:

   B.    Submission Type:
         [ ] New RRTYPE
         [ ] Modification to existing RRTYPE

   C.    Contact Information for submitter:
               Email Address:
               International telephone number:
               Other contact handles:
         (Note: This information will be publicly posted.)

   D.    Motivation for the new RRTYPE application?
         Please keep this part at a high level to inform the Expert and
         reviewers about uses of the RRTYPE. Remember most reviewers
         will be DNS experts that may have limited knowledge of your
         application space.

   E.    Description of the proposed RR type.
         This description can be provided in-line in the template, as an
         attachment or with a publicly available URL:

   F.    What existing RRTYPE or RRTYPEs come closest to filling that
         need and why are they unsatisfactory?

   G.    What mnemonic is requested for the new RRTYPE (optional)?
         Note: this can be left blank and the mnemonic decided after the
         template is accepted.

   H.    Does the requested RRTYPE make use of any existing IANA
         Registry or require the creation of a new IANA sub-registry in
         DNS Parameters?
         If so, please indicate which registry is to be used or created.
         If a new sub-registry is needed, specify the allocation policy
         for it and its initial contents. Also include what the
         modification procedures will be.

   I.    Does the proposal require/expect any changes in DNS
         servers/resolvers that prevent the new type from being
         processed as an unknown RRTYPE (see [RFC3597])?

   J.    Comments:

Annex B: Changes From RFC 5395

   Replace "" with "".

   Drop description of changes from RFC 2929 to RFC 5395 since those
   changes have already happened and we don't need to do them again.

   Updates to boilerplate text.

   Fix Section 5 to say that it is the duty of the applicant, not the
   expert, to post the application to

Normative References

   [RFC1034] - Mockapetris, P., "Domain names - concepts and
   facilities", STD 13, RFC 1034, November 1987.

   [RFC1035] - Mockapetris, P., "Domain names - implementation and
   specification", STD 13, RFC 1035, November 1987.

   [RFC1996] - Vixie, P., "A Mechanism for Prompt Notification of Zone
   Changes (DNS NOTIFY)", RFC 1996, August 1996.

   [RFC2136] - Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
   "Dynamic Updates in the Domain Name System (DNS UPDATE)", RFC 2136,
   April 1997.

   [RFC2181] - Elz, R. and R. Bush, "Clarifications to the DNS
   Specification", RFC 2181, July 1997.

   [RFC2671] - Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC
   2671, August 1999.

   [RFC2845] - Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
   Wellington, "Secret Key Transaction Authentication for DNS (TSIG)",
   RFC 2845, May 2000.

   [RFC2930] - Eastlake 3rd, D., "Secret Key Establishment for DNS (TKEY
   RR)", RFC 2930, September 2000.

   [RFC3425] - Lawrence, D., "Obsoleting IQUERY", RFC 3425, November

   [RFC3597] - Gustafsson, A., "Handling of Unknown DNS Resource Record
   (RR) Types", RFC 3597, September 2003.

   [RFC4020] - Kompella, K. and A. Zinin, "Early IANA Allocation of
   Standards Track Code Points", BCP 100, RFC 4020, February 2005.

   [RFC4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
   Rose, "DNS Security Introduction and Requirements", RFC 4033, March

   [RFC4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
   Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
   March 2005.

   [RFC4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
   Rose, "Protocol Modifications for the DNS Security Extensions", RFC
   4035, March 2005.

   [RFC4635] - Eastlake 3rd, D., "HMAC SHA (Hashed Message
   Authentication Code, Secure Hash Algorithm) TSIG Algorithm
   Identifiers", RFC 4635, August 2006.

   [RFC5226] - Narten, T. and H. Alvestrand, "Guidelines for Writing an
   IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.

   [US-ASCII] - ANSI, "USA Standard Code for Information Interchange",
   X3.4, American National Standards Institute: New York, 1968.

Informative References

   [Dyer1987] - Dyer, S., and F. Hsu, "Hesiod", Project Athena Technical
   Plan - Name Service, April 1987.

   [Moon1981] - Moon, D., "Chaosnet", A.I. Memo 628, Massachusetts
   Institute of Technology Artificial Intelligence Laboratory, June

   [RFC1183] - Everhart, C., Mamakos, L., Ullmann, R., and P.
   Mockapetris, "New DNS RR Definitions", RFC 1183, October 1990.

   [RFC1591] - Postel, J., "Domain Name System Structure and
   Delegation", RFC 1591, March 1994.

   [RFC2606] - Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS
   Names", BCP 32, RFC 2606, June 1999.

   [RFC2673] - Crawford, M., "Binary Labels in the Domain Name System",
   RFC 2673, August 1999.

   [RFC2931] - Eastlake 3rd, E., "DNS Request and Transaction Signatures
   ( SIG(0)s )", RFC 2931, September 2000.

   [RFC3363] - Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T.
   Hain, "Representing Internet Protocol version 6 (IPv6) Addresses in
   the Domain Name System (DNS)", RFC 3363, August 2002.

   [RFC4343] - Eastlake, D., "Domain Name System (DNS) Case
   Insensitivity Clarification", RFC 4343, December 2005.

   [RFC5395] - Eastlake 3rd, D., "Domain Name System (DNS) IANA
   Considerations", BCP 42, RFC 5395, November 2008.

Author's Address

   Donald E. Eastlake 3rd
   Stellar Switches
   155 Beaver Street
   Milford, MA 01757 USA

   Telephone:   +1-508-333-2270

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