One document matched: draft-crocker-dns-attrleaf-06.xml


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<rfc
   category="bcp"
   docName="draft-crocker-dns-attrleaf-06"
   ipr="trust200902">

   <front>
      <title>DNS Scoped Data Through Attribute Leaves</title>
      <author
         fullname="Dave Crocker"
         initials="D."
         surname="Crocker">
         <organization>Brandenburg InternetWorking</organization>
         <address>
            <postal>
               <street>675 Spruce Dr.</street>
               <city>Sunnyvale</city> <region>CA</region> <code>94086</code>
               <country>USA</country>
            </postal>
            <phone>+1.408.246.8253</phone>
            <email>dcrocker@bbiw.net</email>
            <uri>http://bbiw.net/</uri>
            </address>
      </author>
      <date
         year="2011" />
      <!-- <area>Operations</area> -->
      <!-- <workgroup>DNSOP</workgroup> -->
      <keyword>DNS</keyword>
      <keyword>Domain Name System> </keyword>
      <abstract>
         <t>Historically, any DNS RR may occur for any domain name. Recent
            additions have defined DNS leaf nodes that contain a reserved node
            name, beginning with an underscore. The underscore construct is used
            to define a semantic scope for DNS records associated with the
            parent domain. This note explores the nature of this DNS usage and
            defines the "underscore names" registry with IANA. </t>
      </abstract>
   </front>

   <middle>

      <section
         title="Introduction">
         <t>The core DNS technical specifications assign no semantics to domain
            names or their parts, and no constraints upon which resource records
            (RRs) may be associated with particular names. Over time, some leaf
            node names, such as "www" and "ftp" have come to imply support for
            particular services, but this is a matter of operational convention,
            rather than defined protocol
            semantics<!-- and the conventions do not probhibit
            having those services available under other name-->.
            This freedom in the basic technology has permitted a wide range of
            administrative and semantic policies to be used -- in parallel. Data
            semantics have been limited to the specification of particular
            resource records, on the expectation that new ones would be added as
            needed. </t>
         <t>Some recent service enhancements have defined a restricted scope for
            the occurrence of particular resource records. That scope is a leaf
            node, within which the uses of specific resource records can be
            formally defined and constrained. The leaf has a distinguished
            naming convention: It uses a reserved DNS node name that begins with
            an underscore. Because host names are not allowed to use the
            underscore character, this distinguishes the name from all legal
            host name. Effectively, this convention creates a space for
            attributes that are associated with the parent domain, one level
            up.</t>
         <t>An established example is the SRV record <xref
               target="RFC2782" /> which generalizes concepts long-used for
            email routing by the MX record <xref
               target="RFC0974" /><xref
               target="RFC2821" />. The use of special DNS names has significant
            benefits and detriments. Some of these are explored in <xref
               target="RFC5507" />.<list
               style="hanging">
               <t
                  hangText="[Comment]:  ">The terms "resolution context" and
                  "scoping rules" have been suggested, in place of "semantic
                  scope". In order to avoid concern for matters of semantics,
                  this specification uses the term "scoping rules", to create a
                  focus on the mechanics being defined, rather than nuances of
                  interpretation for the mechanism.</t>
            </list>
         </t>
         <t>The scoping feature is particularly useful when generalized resource
            records are used -- notably TXT and SRV. It provides efficient
            separation of one use of them from another. Absent this separation,
            an undifferentiated mass of these RRs are returned to the client
            which then must parse through the internals of the records in the
            hope of finding ones that are relevant. With underscore-based
            scoping, only the relevant RRs are returns.</t>
         <t>This specification discusses the underscore "attribute" enhancement,
            provides an explicit definition of it, and establishes an IANA
            registry for the reserved names that begin with underscore. <list
               style="hanging">
               <t
                  hangText="Discussion Venue:  ">Discussion about this draft is
                  directed to the <eref
                     target="mailto:dnsop@lists.uoregon.edu">dnsop@lists.uoregon.edu</eref>
                  mailing list of the <eref
                     target="http://ietf.org/html.charters/dnsop-charter.html">IETF
                     DNSOP Working Group</eref>.</t>
            </list>
         </t>
      </section>

      <section
         title="Scaling Benefits and TXT and SRV Resource Records">
         <t>Some resource records are generic and support a variety of uses.
            Each additional use defines its own rules and, possibly, its own
            internal syntax and node-naming conventions to distinguish among
            particular types. The TXT and SRV records are the notable examples.
            Used freely, some of these approaches scale poorly, particularly
            when the same RR can be present in the same leaf node, but with
            different uses. An increasingly-popular approach, with excellent
            scaling properties, uses an underscore-based name to a define place
            in the DNS that is constrained to particular uses for particular
            RRs. This means that a direct lookup produces only the desired
            records, at no greater cost than a typical lookup.</t>
         <t> In the case of TXT records, different uses have developed largely
            without coordination. One side-effect is that there is no
            consistently distinguishable internal syntax for the record; even
            internal inspection might not be a reliable means of distinguishing
            among the different uses. Underscore-based names therefore provide
            an administrative way of separating TXT records that might have
            different uses, but otherwise would have no syntactic markers for
            distinguishing among them. </t>
         <t>In the case of the SRV RR distinguishing among different types of
            use was part of the design. <xref
               target="RFC2782" /> The SRV specification serves as a template,
            defining an RR that may only be used for specific applications when
            there is an additional specification. The template definition
            includes reference to tables of names from which underscore-names
            should be drawn. The set of <service> names is defined in
            terms of other IANA tables, namely any table with symbolic names.
            The other SRV naming field is <proto>, although its pool of
            names is not explicitly defined.</t>
      </section>

      <section
         anchor="underfun"
         title="Underscore DNS          Registry Function">
         <t>This specification defines a registry for DNS nodes names, used to
            define scope of use for specific resource records (RR). A given name
            defines a specific, constrained context for the use of such records.
            This does not constrain the use of other resource records that are
            not specified. The purpose of the registry is to avoid collisions
            resulting from the use of the same underscore name, for different
            applications. </t>
         <t>Structurally, the registry is defined as a single, flat table of
            names that begin with underscore. In some cases, such as for SRV, an
            underscore name might be multi-part, as a sequence of names.
            Semantically, this is a hierarchical model, thereby making a flat
            registry unexpected.</t>
         <t>The registry requires such hierarchies to be registered as a
            combinatorial case analysis set, with each entry being a full
            sequence of underscore names. Given a scheme that is actually
            structured, this flat design is inelegant. However it has the
            benefit of being extremely simple, with the added advantage of being
            easier for readers to understand, as long as these cases are small
            and few.</t>
         <texttable
            title="Example of Underscore Names">
            <ttcol
               align="left">NAME</ttcol>
            <c>_service1</c>
            <c>_service2._protoB</c>
            <c>_service3._protoC</c>
            <c>_service3._protoC</c>
            <c>_service4._protoD._useX</c>
            <c>_protoE._region._authority</c>
         </texttable>
         <t>The flat registry design: <list
               style="symbols">
               <t>provides significantly simpler administration than is needed
                  for hierarchical tables, simples, and</t>
               <t>is significantly simpler for readers to understand and is
                  likely to produce fewer programming or administration
                  errors.</t>
            </list>
         </t>
         <t />

      </section>

      <section
         anchor="regdef"
         title="DNS Underscore Registry Definition">
         <t>A registry entry MUST contain: <list>
               <t>
                  <list
                     style="hanging">
                     <t
                        hangText="Name:  ">Specifies a textual name for a scoped
                        portion of the DNS. The name will usually be taken from
                        the specification cited in the "Purpose" column and is
                        intended for use in discussions about the entry.</t>
                     <t
                        hangText="DNS Label(s):  ">Specifies a sequence of one
                        or more underscore names that define a single name
                        reservation. </t>
                     <t
                        hangText="Constraints:  ">Specifies any restrictions on
                        use of the name.</t>
                     <t
                        hangText="RR(s):  ">Lists the RRs that are defined for
                        use within this scope.</t>
                     <t
                        hangText="References">Lists specifications that define
                        the records and their use under this Name. </t>
                     <t
                        hangText="Purpose:  ">Specifies the particular
                        purpose/use for specific RR(s), defined for use within
                        the scope of the registered underscore name.</t>
                  </list>
               </t>
            </list>
         </t>
      </section>


      <section
         title="IANA Considerations">
         <t> Per <xref
               target="RFC2434" />, IANA is requested to establish a DNS
            Underscore Name Registry, for DNS node names that begin with the
            underscore character (_) and have been specified in any published
            RFC, or are documented by a specification published by another
            standards organization. The contents of each entry are defined in <xref
               target="regdef" />.</t>

         <texttable
            align="left"
            anchor="underscope"
            title="DNS Underscore SCOPE Name Registry                 (with
            initial values)">

            <ttcol>NAME</ttcol>
            <ttcol>DNS LABEL</ttcol>
            <ttcol>CONSTRAINTS</ttcol>
            <ttcol>RR(s)</ttcol>
            <ttcol>REFERENCES</ttcol>
            <ttcol>PURPOSE</ttcol>
            <!---->

            <c>SRV TCP</c>
            <c>_srv._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC2782" />
            </c>
            <c> SRV template </c>
            <!--  -->

            <c>SRV UDP</c>
            <c>_srv._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC2782" />
            </c>
            <c> SRV template </c>
            <!--  -->


            <c>LDAP SRV</c>
            <c>_ldap._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC2782" />
            </c>
            <c> LDAP server </c>
            <!--  -->

            <c>SIP TCP</c>
            <c>_sip._tcp</c>
            <c />
            <c>NAPTR</c>
            <c><xref
                  target="RFC3263" />, <xref
                  target="RFC6011" />
            </c>
            <c>Locating SIP Servers and UA configuration</c>
            <!---->

            <c>SIPS TCP</c>
            <c>_sips._tcp</c>
            <c />
            <c>NAPTR</c>
            <c><xref
                  target="RFC3263" />, <xref
                  target="RFC6011" />
            </c>
            <c>Locating SIP Servers and UA configuration</c>
            <!---->

            <c>SIP UDP</c>
            <c>_sip._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3263" />, <xref
                  target="RFC6011" />
            </c>
            <c>Locating SIP servers and UA configuration</c>
            <!---->

            <c>SPF</c>
            <c>_spf</c>
            <c />
            <c>TXT</c>
            <c>
               <xref
                  target="RFC4408" />
            </c>
            <c>Authorized IP addresses for sending mail</c>
            <!---->

            <c>DKIM</c>
            <c>_domainkey</c>
            <c />
            <c>TXT</c>
            <c>
               <xref
                  target="RFC4871" />
            </c>
            <c>Public key for verifying DKIM signature.</c>

            <c>ADSP</c>
            <c>_adsp._domainkey</c>
            <c> </c>
            <c>TXT</c>
            <c>
               <xref
                  target="RFC5617" />
            </c>
            <c>Published DKIM usage practices</c>
            <!-- -->

            <!---->

            <c>PKI LDAP</c>
            <c>_PKIXREP._ldap</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4386" />
            </c>
            <c>LDAP PKI Repository</c>
            <!-- -->

            <c>PKI HTTP</c>
            <c>_PKIXREP._http</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4386" />
            </c>
            <c>HTTP PKI Repository</c>
            <!-- -->

            <c>PKI OCSP</c>
            <c>_PKIXREP._ocsp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4386" />
            </c>
            <c>OCSP PKI Repository</c>
            <!-- -->

            <c>VBR</c>
            <c>_vouch</c>
            <c> </c>
            <c>TXT</c>
            <c>
               <xref
                  target="RFC5518" />
            </c>
            <c>Vouch-by-refererence domain assertion</c>
            <!-- -->

            <c>DDDS</c>
            <c>--unknown!--</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3404" />
            </c>
            <c>Mapping DDDS query to DNS records</c>
            <!-- -->

            <c>SOAP BEEP</c>
            <c>_soap-beep._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4227" />
            </c>
            <c>SOAP over BEEP lookup, when no port specified</c>
            <!-- -->


            <c>XMLRPC BEEP</c>
            <c>_xmlrpc-beep._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3529" />
            </c>
            <c>Resolve url for XML-RPC using BEEP</c>
            <!-- -->

            <c>Diameter SCTP</c>
            <c>_diameter._sctp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3588" />
            </c>
            <c>Diameter rendezvous over SCTP</c>
            <!-- -->

            <c>Diameter TCP</c>
            <c>_diameter._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3588" />
            </c>
            <c>Diameter rendezvous over TCP</c>
            <!-- -->

            <c>Tunnel</c>
            <c>_tunnel._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3620" />
            </c>
            <c>Finding the appropriate address for tunneling into a particular
               domain</c>
            <!-- -->

            <c>SLP TCP</c>
            <c>_slpda._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3832" />
            </c>
            <c>Discovering desired services in given DNS domains</c>
            <!-- -->

            <c>SLP UDP</c>
            <c>_slpda._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3832" />
            </c>
            <c>Discovering desired services in given DNS domains</c>
            <!-- -->

            <c>IM</c>
            <c>_im</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3861" />
            </c>
            <c>Instant Messaging address resolution</c>
            <!-- -->

            <c>Pres</c>
            <c>_pres</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3861" />
            </c>
            <c>Presence address resolution</c>
            <!-- -->

            <c>Msg Track</c>
            <c>_mtqp._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC3887" />
            </c>
            <c>Assist in determining the path that a particular message has
               taken through a messaging system</c>
            <!-- -->


            <c>XMPP Client</c>
            <c>_xmpp-client._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC6120" />
            </c>
            <c>XMPP client lookup of server</c>
            <!-- -->


            <c>XMPP Server</c>
            <c>_xmpp-server._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC6120" />
            </c>
            <c>XMPP server-server lookup</c>
            <!-- -->

            <c>DDDS SRV</c>
            <c>_???</c>
            <c>(unable to discern details. /dcrocker)</c>
            <c>SRV (and NAPTR?)</c>
            <c>
               <xref
                  target="RFC3958" />
            </c>
            <c>Map domain name, application service name, and application
               protocol dynamically to target server and port</c>
            <!-- -->

            <c>Kerberos TCP</c>
            <c>_kerberos._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4120" />
            </c>
            <c>purpose</c>
            <!-- -->

            <c>Kerberos UDP</c>
            <c>_kerberos._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4120" />
            </c>
            <c>purpose</c>
            <!-- -->

            <c>PKI LDAP</c>
            <c>_pkixrep._ldap</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4386" />
            </c>
            <c>Enables certificate-using systems to locate PKI repositories</c>
            <!-- -->


            <c>PKI HTTP</c>
            <c>_pkixrep._http</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4386" />
            </c>
            <c>Enables certificate-using systems to locate PKI repositories</c>
            <!-- -->


            <c>PKI OCSP</c>
            <c>_pkixrep._ocsp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4386" />
            </c>
            <c>Enables certificate-using systems to locate PKI repositories</c>
            <!-- -->

            <c>Cert Store</c>
            <c>_certificates._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4387" />
            </c>
            <c>Obtain certificates and certificate revocation lists (CRLs) from
               PKI repositories</c>
            <!-- -->

            <c>Cert Revocation Store</c>
            <c>_crls._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4387" />
            </c>
            <c>Obtain certificates and certificate revocation lists (CRLs) from
               PKI repositories</c>
            <!-- -->

            <c>PGP Key Store</c>
            <c>pgpkeys._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4387" />
            </c>
            <c>Obtain certificates and certificate revocation lists (CRLs) from
               PKI repositories</c>
            <!-- -->

            <c>MSRP Relay Locator</c>
            <c>_msrp._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC4976" />
            </c>
            <c>purpose</c>
            <!-- -->

            <c>Mobile IPv6 Bootstrap</c>
            <c>_mip6._ipv6</c>
            <c />
            <c>SRV</c>
            <c><xref
                  target="RFC5026" />, <xref
                  target="RFC5555" /></c>
            <c>Bootstrap Mobile IPv6 Home Agent information from non-topological
               information</c>
            <!-- -->

            <c>Digital Video Broadcasting TCP</c>
            <c>_dvbservdsc._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5328" />
            </c>
            <c>Discover non-default DVB entry points addresses</c>
            <!-- -->

            <c>Digital Video Broadcasting UDP</c>
            <c>_dvbservdsc._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5328" />
            </c>
            <c>Discover non-default DVB entry points addresses</c>
            <!-- -->

            <c>CAPWAP AC</c>
            <c>_capwap-control._udp</c>
            <c />
            <c>rrs</c>
            <c>
               <xref
                  target="RFC5415" />
            </c>
            <c>Discover the CAPWAP AC address(es)</c>
            <!-- -->

            <c>IM SIP</c>
            <c>_im._sip</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5509" />
            </c>
            <c>For resolving Instant Messaging and Presence services with
               SIP</c>
            <!-- -->

            <c>Pres SIP</c>
            <c>_pres._sip</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5509" />
            </c>
            <c>For resolving Instant Messaging and Presence services with
               SIP</c>
            <!-- -->

            <c>IEEE 802.21 Mobility TCP</c>
            <c>_mihis._tcp</c>
            <c />
            <c>NAPTR, SRV</c>
            <c>
               <xref
                  target="RFC5679" />
            </c>
            <c>Discovering servers that provide IEEE 802.21-defined Mobility
               Services</c>
            <!-- -->

            <c>IEEE 802.21 Mobility UDP</c>
            <c>_mihis._udp</c>
            <c />
            <c>NAPTR, SRV</c>
            <c>
               <xref
                  target="RFC5679" />
            </c>
            <c>Discovering servers that provide IEEE 802.21-defined Mobility
               Services</c>
            <!-- -->

            <c>STUN Client/Server TCP</c>
            <c>_stun._.tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5389" />
            </c>
            <c>Find a STUN server</c>
            <!-- -->

            <c>STUN Client/Server UDP</c>
            <c>_stun._.udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5389" />
            </c>
            <c>Find a STUN server</c>
            <!-- -->

            <c>STUN Client/Server TLS</c>
            <c>_stuns._.tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5389" />
            </c>
            <c>Find a STUN server</c>
            <!-- -->


            <c>TURN TCP</c>
            <c>_turn._tcp</c>
            <c />
            <c>SRV</c>
            <c><xref
                  target="RFC5766" />, <xref
                  target="RFC5928" /></c>
            <c>Control the operation of a relay to bypass NAT</c>
            <!-- -->


            <c>TURN UDP</c>
            <c>_turn._udp</c>
            <c />
            <c>SRV</c>
            <c><xref
                  target="RFC5766" />, <xref
                  target="RFC5928" /></c>
            <c>Control the operation of a relay to bypass NAT</c>
            <!-- -->

            <c>TURN TLS</c>
            <c>_turns._tcp</c>
            <c />
            <c>SRV</c>
            <c><xref
                  target="RFC5766" />, <xref
                  target="RFC5928" /></c>
            <c>Control the operation of a relay to bypass NAT</c>
            <!-- -->

            <c>STUN NAT Behavior Discovery TCP</c>
            <c>_stun-behavior._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5780" />
            </c>
            <c>Discover the presence and current behavior of NATs and firewalls
               between the STUN client and the STUN server</c>
            <!-- -->

            <c>STUN NAT Behavior Discovery UDP</c>
            <c>_stun-behavior._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5780" />
            </c>
            <c>Discover the presence and current behavior of NATs and firewalls
               between the STUN client and the STUN server</c>
            <!-- -->

            <c>STUN NAT Behavior Discovery TLS</c>
            <c>_stun-behaviors._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5780" />
            </c>
            <c>Discover the presence and current behavior of NATs and firewalls
               between the STUN client and the STUN server</c>
            <!-- -->

            <c>Sieve Management</c>
            <c>_sieve._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5804" />
            </c>
            <c>Manage Sieve scripts on a remote server</c>
            <!-- -->

            <c>AFS VLDB</c>
            <c>_afs3-vlserver._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5864" />
            </c>
            <c>Locate services for the AFS distributed file system</c>
            <!-- -->


            <c>AFS PTS</c>
            <c>_afs3-prserver._udp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC5864" />
            </c>
            <c>Locate services for the AFS distributed file system</c>
            <!-- -->

            <c>Mail MSA Submission</c>
            <c>_submission._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC6186" />
            </c>
            <c>Locate email services</c>
            <!-- -->

            <c>IMAP</c>
            <c>_imap._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC6186" />
            </c>
            <c>Locate email services</c>
            <!-- -->

            <c>IMAP TLS</c>
            <c>_imaps._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC6186" />
            </c>
            <c>Locate email services</c>
            <!-- -->

            <c>POP</c>
            <c>_pop3._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC6186" />
            </c>
            <c>Locate email services</c>
            <!-- -->

            <c>POP TLS</c>
            <c>_pop3s._tcp</c>
            <c />
            <c>SRV</c>
            <c>
               <xref
                  target="RFC6186" />
            </c>
            <c>Locate email services</c>
            <!-- -->

            <!--  Table entry template 
       <c>name</c>
       <c>_label</c>
       <c>constraints</c>
       <c>_</c>
       <c><xref
       target="" /></c>
       <c>purpose</c>
       <!-\- -\->
-->
         </texttable>

      </section>

      <section
         title="Related Registries">
         <t>Numerous specifications have defined their own, independent
            registries for use of underscore names. It is likely that adoption
            of the proposed, integrated registry should render these piecemeal
            registries obsolete</t>

         <t>Registries that are candidates for replacement include: <list>
               <t>Instant Messaging SRV Protocol Label Registry</t>
               <t>Public Key Infrastructure using X.509 (PKIX) Parameters</t>
               <t>Presence SRV Protocol Label Registry</t>
            </list>
         </t>

      </section>


      <section
         title="Security Considerations">
         <t>This memo raises no security issues.</t>
      </section>
   </middle>


   <back>

      <references
         title="Normative References">
         <reference
            anchor="RFC2434">
            <front>
               <title>Guidelines for Writing an IANA Considerations Section in
                  RFCs</title>
               <author
                  fullname="T. Narten"
                  initials="T."
                  surname="Narten">
                  <organization>IBM</organization>
               </author>
               <author
                  fullname="H. Alvestrand"
                  initials="H."
                  surname="Alvestrand">
                  <organization>Maxware</organization>
               </author>
               <date
                  month="October"
                  year="1998" />
            </front>
            <seriesInfo
               name="RFC"
               value="2434" />
         </reference>

      </references>


      <references
         title="References -- Informative">

         <reference
            anchor="RFC2821">
            <front>
               <title>Simple Mail Transfer Protocol</title>
               <author
                  fullname="J. Klensin"
                  initials="J."
                  surname="Klensin">
                  <organization />
               </author>
               <date
                  month="April"
                  year="2001" />
               <abstract>
                  <t>This document is a self-contained specification of the
                     basic protocol for the Internet electronic mail transport.
                     [STANDARDS-TRACK]</t>
               </abstract>
            </front>

            <seriesInfo
               name="RFC"
               value="2821" />
            <format
               octets="192504"
               target="http://www.rfc-editor.org/rfc/rfc2821.txt"
               type="TXT" />
         </reference>


         <reference
            anchor="RFC0974">
            <front>
               <title>Mail routing and the domain system</title>
               <author
                  fullname="Craig Partridge"
                  initials="C."
                  surname="Partridge">
                  <organization>Bolt Baranek and Newman (BBN) Laboratories Inc.,
                     CSNET CIC</organization>
               </author>
               <date
                  day="1"
                  month="January"
                  year="1986" />
            </front>

            <seriesInfo
               name="RFC"
               value="974" />
            <format
               octets="18581"
               target="http://www.rfc-editor.org/rfc/rfc974.txt"
               type="TXT" />
         </reference>



         <reference
            anchor="RFC2782">
            <front>
               <title
                  abbrev="DNS SRV RR">A DNS RR for specifying the location of
                  services (DNS SRV)</title>
               <author
                  fullname="Arnt Gulbrandsen"
                  initials="A."
                  surname="Gulbrandsen">
                  <organization>Troll Tech</organization>
                  <address>
<postal>
<street>Waldemar Thranes gate 98B</street>
<city>Oslo</city>
<region />
<code>N-0175</code>
<country>NO</country></postal>
<phone>+47 22 806390</phone>
<facsimile>+47 22 806380</facsimile>
<email>arnt@troll.no</email></address>
               </author>
               <author
                  fullname="Paul Vixie"
                  initials="P."
                  surname="Vixie">
                  <organization>Internet Software Consortium</organization>
                  <address>
<postal>
<street>950 Charter Street</street>
<city>Redwood City</city>
<region>CA</region>
<code>94063</code>
<country>US</country></postal>
<phone>+1 650 779 7001</phone></address>
               </author>
               <author
                  fullname="Levon Esibov"
                  initials="L."
                  surname="Esibov">
                  <organization>Microsoft Corporation</organization>
                  <address>
<postal>
<street>One Microsoft Way</street>
<city>Redmond</city>
<region>WA</region>
<code>98052</code>
<country>US</country></postal>
<email>levone@microsoft.com</email></address>
               </author>
               <date
                  month="February"
                  year="2000" />
               <abstract>
                  <t>This document describes a DNS RR which specifies the
                     location of the server(s) for a specific protocol and
                     domain.</t>
               </abstract>
            </front>

            <seriesInfo
               name="RFC"
               value="2782" />
            <format
               octets="24013"
               target="http://www.rfc-editor.org/rfc/rfc2782.txt"
               type="TXT" />
         </reference>

         <reference
            anchor="RFC3263">
            <front>
               <title>Session Initiation Protocol (SIP): Locating SIP
                  Servers</title>
               <author
                  fullname="J. Rosenberg"
                  initials="J."
                  surname="Rosenberg">
                  <organization />
               </author>
               <author
                  fullname="H. Schulzrinne"
                  initials="H."
                  surname="Schulzrinne">
                  <organization />
               </author>
               <date
                  month="June"
                  year="2002" />
               <abstract>
                  <t>The Session Initiation Protocol (SIP) uses DNS procedures
                     to allow a client to resolve a SIP Uniform Resource
                     Identifier (URI) into the IP address, port, and transport
                     protocol of the next hop to contact. It also uses DNS to
                     allow a server to send a response to a backup client if the
                     primary client has failed. This document describes those
                     DNS procedures in detail. [STANDARDS-TRACK]</t>
               </abstract>
            </front>

            <seriesInfo
               name="RFC"
               value="3263" />
            <format
               octets="42310"
               target="http://www.rfc-editor.org/rfc/rfc3263.txt"
               type="TXT" />
         </reference>

         <reference
            anchor="RFC3404">
            <front>
               <title>Dynamic Delegation Discovery System (DDDS) Part Four: The
                  Uniform Resource Identifiers (URI) Resolution
                  Application</title>
               <author
                  fullname="M. Mealling"
                  initials="M."
                  surname="MMealling" />
               <date
                  month="October"
                  year="2002" />
            </front>
            <seriesInfo
               name="RFC"
               value="3404" />
         </reference>


         <reference
            anchor="RFC3529">
            <front>
               <title>Using Extensible Markup Language-Remote Procedure Calling
                  (XML-RPC) in Blocks Extensible Exchange Protocol (BEEP) </title>
               <author
                  fullname="W. Harold"
                  initials="W"
                  surname="Harold">
                  <organization>IBM</organization>
               </author>
               <date
                  month="April"
                  year="2003" />
            </front>
            <seriesInfo
               name="RFC"
               value="3529" />
         </reference>



         <reference
            anchor="RFC3588">
            <front>
               <title>Diameter Base Protocol </title>
               <author
                  fullname="P. Calhoun"
                  initials="P."
                  surname="Calhoun">
                  <organization>Airespace, Inc.</organization>
               </author>
               <author
                  fullname="J. Loughney"
                  initials="J."
                  surname="Loughney">
                  <organization>Nokia</organization>
               </author>
               <author
                  fullname="E. Guttman"
                  initials="E."
                  surname="Guttman">
                  <organization>Sun Microsystems, Inc.</organization>
               </author>
               <author
                  fullname="G. Zorn"
                  initials="G."
                  surname="Zorn">
                  <organization>Cisco Systems, Inc</organization>
               </author>
               <author
                  fullname="J. Arkko"
                  initials="J."
                  surname="Arkko">
                  <organization>Ericsson</organization>
               </author>
               <date
                  month="September"
                  year="2003" />
            </front>
         </reference>


         <reference
            anchor="RFC3620">
            <front>
               <title>The TUNNEL Profile</title>
               <author
                  fullname="D. New"
                  initials="D."
                  surname="New" />
               <date
                  month="October"
                  year="2003" />
            </front>
            <seriesInfo
               name="RFC"
               value="3620" />
         </reference>


         <reference
            anchor="RFC3861">
            <front>
               <title>Address Resolution for Instant Messaging and
                  Presence</title>
               <author
                  fullname="J. Peterson"
                  initials="J."
                  surname="Peterson">
                  <organization>Neustar</organization>
               </author>
               <date
                  month="August"
                  year="2004" />
            </front>
            <seriesInfo
               name="RFC"
               value="3861" />
         </reference>


         <reference
            anchor="RFC3832">
            <front>
               <title>Remote Service Discovery in the Service Location Protocol
                  (SLP) via DNS SRV</title>
               <author
                  fullname="W. Zhao"
                  initials=""
                  surname="">
                  <organization>Columbia University</organization>
               </author>
               <author
                  fullname="H. Schulzrinne"
                  initials=""
                  surname="">
                  <organization>Columbia University</organization>
               </author>
               <author
                  fullname="E. Guttman"
                  initials=""
                  surname="">
                  <organization>Sun Microsystems</organization>
               </author>
               <author
                  fullname="C. Bisdikian"
                  initials=""
                  surname="">
                  <organization>IBM</organization>
               </author>
               <author
                  fullname="W. Jerome"
                  initials=""
                  surname="">
                  <organization>IBM</organization>
               </author>
               <date
                  month="July"
                  year="2004" />
            </front>
         </reference>








         <reference
            anchor="RFC3887">
            <front>
               <title>Message Tracking Query Protocol</title>
               <author />
               <date
                  month="September"
                  year="2007" />
            </front>
         </reference>

         <reference
            anchor="RFC3958">
            <front>
               <title>Domain-Based Application Service Location Using SRV RRs
                  and the Dynamic Delegation Discovery Service (DDDS)</title>
               <author
                  fullname="L. Daigle"
                  initials="L."
                  surname="Daigle">
                  <organization>VeriSign, Inc.</organization>
               </author>
               <author
                  fullname="A. Newton"
                  initials="A."
                  surname="Newton">
                  <organization>VeriSign, Inc.</organization>
               </author>
               <date
                  month="January"
                  year="2005" />
            </front>
            <seriesInfo
               name="RFC"
               value="3958" />
         </reference>

         <reference
            anchor="RFC4120">
            <front>
               <title>The Kerberos Network Authentication Service (V5)</title>
               <author
                  fullname="C. Neuman"
                  initials=""
                  surname="">
                  <organization>USC-ISI</organization>
               </author>
               <author
                  fullname="T. Yu"
                  initials=""
                  surname="">
                  <organization>MIT</organization>
               </author>
               <author
                  fullname="S. Hartman"
                  initials=""
                  surname="">
                  <organization>MIT</organization>
               </author>
               <author
                  fullname="K. Raeburn"
                  initials=""
                  surname="">
                  <organization>MIT</organization>
               </author>
               <date
                  month="July"
                  year="2005" />
            </front>
            <seriesInfo
               name="RFC"
               value="4120" />
         </reference>


         <reference
            anchor="RFC4227">
            <front>
               <title>Using the Simple Object Access Protocol (SOAP) in Blocks
                  Extensible Exchange Protocol (BEEP)</title>
               <author
                  fullname="E. O'Tuathail"
                  initials="E."
                  surname="O'Tuathail">
                  <organization>Clipcode.com</organization>
               </author>
               <author
                  fullname="M. Rose"
                  initials="M."
                  surname="Rose">
                  <organization>Dover Beach Consulting, Inc.</organization>
               </author>
               <date
                  month="January"
                  year="2006" />
            </front>
            <seriesInfo
               name="RFC"
               value="4227" />
         </reference>

         <reference
            anchor="RFC4386">
            <front>
               <title>Internet X.509 Public Key Infrastructure: Repository
                  Locator Service</title>
               <author
                  fullname="S. Boeyen"
                  initials="S."
                  surname="Boeyen">
                  <organization>Entrust Inc.</organization>
               </author>
               <author
                  fullname="P. Hallam-Baker"
                  initials="P."
                  surname="Hallam-Baker">
                  <organization>VeriSign Inc.</organization>
               </author>
               <date
                  month="February"
                  year="2006" />
            </front>
         </reference>


         <reference
            anchor="RFC4387">
            <front>
               <title>Internet X.509 Public Key Infrastructure Operational
                  Protocols: Certificate Store Access via HTTP</title>
               <author
                  fullname="P. Gutmann"
                  initials="P."
                  role="editor"
                  surname="Gutmann">
                  <organization>University of Auckland</organization>
               </author>
               <date
                  month="February"
                  year="2006" />
            </front>
            <seriesInfo
               name="RFC"
               value="4387" />
         </reference>

         <reference
            anchor="RFC4408">

            <front>
               <title>Sender Policy Framework (SPF) for Authorizing Use of
                  Domains in E-Mail, Version 1</title>
               <author
                  fullname="M. Wong"
                  initials="M."
                  surname="Wong">
                  <organization />
               </author>
               <author
                  fullname="W. Schlitt"
                  initials="W."
                  surname="Schlitt">
                  <organization />
               </author>
               <date
                  month="April"
                  year="2006" />
               <abstract>
                  <t>E-mail on the Internet can be forged in a number of ways.
                     In particular, existing protocols place no restriction on
                     what a sending host can use as the reverse-path of a
                     message or the domain given on the SMTP HELO/EHLO commands.
                     This document describes version 1 of the ender Policy
                     Framework (SPF) protocol, whereby a domain may explicitly
                     authorize the hosts that are allowed to use its domain
                     name, and a receiving host may check such authorization.
                     This memo defines an Experimental Protocol for the Internet
                     community.</t>
               </abstract>
            </front>

            <seriesInfo
               name="RFC"
               value="4408" />
            <format
               octets="105009"
               target="http://www.rfc-editor.org/rfc/rfc4408.txt"
               type="TXT" />
         </reference>

         <reference
            anchor="RFC5617">
            <front>
               <title>DomainKeys Identified Mail (DKIM) Author Domain Signing
                  Practices (ADSP)</title>
               <author
                  fullname="E. Allman"
                  initials=""
                  surname="">
                  <organization>Sendmail, Inc.</organization>
               </author>
               <author
                  fullname="J. Fenton"
                  initials=""
                  surname="">
                  <organization>Cisco Systems, Inc.</organization>
               </author>
               <author
                  fullname="M. Delany"
                  initials=""
                  surname="">
                  <organization>Yahoo! Inc.</organization>
               </author>
               <author
                  fullname="J. Levine"
                  initials=""
                  surname="">
                  <organization>Taughannock Networks</organization>
               </author>
               <date
                  month="August"
                  year="2009" />
            </front>
         </reference>

         <reference
            anchor="RFC4871">
            <front>
               <title>DomainKeys Identified Mail (DKIM) Signatures</title>
               <author
                  fullname="E. Allman"
                  initials="E."
                  surname="Allman">
                  <organization />
               </author>

               <author
                  fullname="J. Callas"
                  initials="J."
                  surname="Callas">
                  <organization />
               </author>

               <author
                  fullname="M. Delany"
                  initials="M."
                  surname="Delany">
                  <organization />
               </author>

               <author
                  fullname="M. Libbey"
                  initials="M."
                  surname="Libbey">
                  <organization />
               </author>

               <author
                  fullname="J. Fenton"
                  initials="J."
                  surname="Fenton">
                  <organization />
               </author>

               <author
                  fullname="M. Thomas"
                  initials="M."
                  surname="Thomas">
                  <organization />
               </author>

               <date
                  month="May"
                  year="2007" />

               <abstract>
                  <t>DomainKeys Identified Mail (DKIM) defines a domain-level
                     authentication framework for email using public-key
                     cryptography and key server technology to permit
                     verification of the source and contents of messages by
                     either Mail Transfer Agents (MTAs) or Mail User Agents
                     (MUAs). The ultimate goal of this framework is to permit a
                     signing domain to assert responsibility for a message, thus
                     protecting message signer identity and the integrity of the
                     messages they convey while retaining the functionality of
                     Internet email as it is known today. Protection of email
                     identity may assist in the global control of "spam" and
                     "phishing". [STANDARDS TRACK]</t>
               </abstract>
            </front>

            <seriesInfo
               name="RFC"
               value="4871" />
            <format
               octets="166054"
               target="http://www.rfc-editor.org/rfc/rfc4871.txt"
               type="TXT" />
         </reference>


         <reference
            anchor="RFC4976">
            <front>
               <title>Relay Extensions for the Message Session Relay Protocol
                  (MSRP)</title>
               <author
                  fullname="C. Jennings"
                  initials="C."
                  surname="Jennings">
                  <organization>Cisco Systems, Inc.</organization>
               </author>
               <author
                  fullname="R. Mahy"
                  initials="R."
                  surname="Mahy">
                  <organization>Plantronics</organization>
               </author>
               <author
                  fullname="A. B. Roach"
                  initials=""
                  surname="Roach">
                  <organization>Estacado Systems</organization>
               </author>
               <date
                  month="September"
                  year="2007" />
            </front>
            <seriesInfo
               name="RFC"
               value="4976" />
         </reference>

         <reference
            anchor="RFC5026">
            <front>
               <title>Mobile IPv6 Bootstrapping in Split Scenario</title>
               <author
                  fullname="G. Giaretta"
                  initials="G."
                  role="editor"
                  surname="Giaretta">
                  <organization>Qualcomm</organization>
               </author>
               <author
                  fullname="J. Kempf"
                  initials="J."
                  surname="Kempf">
                  <organization>DoCoMo Labs USA</organization>
               </author>
               <author
                  fullname="V. Devarapalli"
                  initials="V."
                  role="editor"
                  surname="Devarapalli">
                  <organization>Azaire Networks</organization>
               </author>
               <date
                  month="October"
                  year="2007" />
            </front>
            <seriesInfo
               name="RFC"
               value="5026" />
         </reference>


         <reference
            anchor="RFC5328">
            <front>
               <title>A Uniform Resource Name (URN) Namespace for the Digital
                  Video Broadcasting Project (DVB)</title>
               <author
                  fullname="A. Adolf"
                  initials="A."
                  surname="Adolf">
                  <organization>Micronas GmbH</organization>
               </author>
               <author
                  fullname="P. MacAvock"
                  initials="P."
                  surname="MacAvock">
                  <organization>DVB Project</organization>
               </author>
               <date
                  month="September"
                  year="2008" />
            </front>
            <seriesInfo
               name="RFC"
               value="5328" />
         </reference>


         <reference
            anchor="RFC5389">
            <front>
               <title>Session Traversal Utilities for NAT (STUN)</title>
               <author
                  fullname="J. Rosenberg"
                  initials=""
                  surname="Rosenberg">
                  <organization>Cisco</organization>
               </author>
               <author
                  fullname="R. Mahy"
                  initials=""
                  surname="Mahy">
                  <organization>Cisco</organization>
               </author>
               <author
                  fullname="P. Matthews"
                  initials=""
                  surname="Matthews" />
               <author
                  fullname="D. Wing"
                  initials=""
                  surname="Wing">
                  <organization>Cisco</organization>
               </author>
               <date
                  month="October"
                  year="2008" />
            </front>
            <seriesInfo
               name="RFC"
               value="5389" />
         </reference>


         <reference
            anchor="RFC5507">
            <front>
               <title />
               <author
                  fullname="P. Faltstrom"
                  initials="P."
                  role="editor"
                  surname="Faltstrom">
                  <organization>IAB</organization>
               </author>
               <author
                  fullname="R. Austein"
                  initials="R."
                  role="editor"
                  surname="Austein">
                  <organization>IAB</organization>
               </author>

               <date
                  month="April"
                  year="2009" />
            </front>
            <seriesInfo
               name="RFC"
               value="5507" />
         </reference>


         <reference
            anchor="RFC5415">
            <front>
               <title>Control And Provisioning of Wireless Access Points
                  (CAPWAP) Protocol Specification</title>
               <author
                  fullname="P. Calhoun"
                  initials="P."
                  role="editor"
                  surname="Calhoun">
                  <organization>Cisco Systems, Inc.</organization>
               </author>
               <author
                  fullname="M. Montemurro"
                  initials="M."
                  role="editor"
                  surname="Montemurro">
                  <organization>Research In Motion</organization>
               </author>
               <author
                  fullname="D. Stanley"
                  initials="D."
                  role="editor"
                  surname="Stanley">
                  <organization>Aruba Networks</organization>
               </author>
               <date
                  month="March"
                  year="2009" />
            </front>
            <seriesInfo
               name="RFC"
               value="5415" />

         </reference>

         <reference
            anchor="RFC5509">
            <front>
               <title>Internet Assigned Numbers Authority (IANA) Registration of
                  Instant Messaging and Presence DNS SRV RRs for the Session
                  Initiation Protocol (SIP)</title>
               <author
                  fullname="S. Loreto"
                  initials="S."
                  surname="Loreto">
                  <organization>Ericsson</organization>
               </author>
               <date
                  month="April"
                  year="2009" />
            </front>
            <seriesInfo
               name="RFC"
               value="5509" />
         </reference>


         <reference
            anchor="RFC5518">
            <front>
               <title>Vouch By Reference</title>
               <author
                  fullname="P. Hoffman"
                  initials="P."
                  surname="Hoffman">
                  <organization>Domain Assurance Council</organization>
               </author>
               <author
                  fullname="J. Levine"
                  initials="J."
                  surname="Levine">
                  <organization>Domain Assurance Council</organization>
               </author>
               <author
                  fullname="A. Hathcock"
                  initials="A."
                  surname="Hathcock">
                  <organization>Alt-N Technologies</organization>
               </author>
               <date
                  month="April"
                  year="2009" />
            </front>
            <seriesInfo
               name="RFC5"
               value="5518" />
         </reference>


         <reference
            anchor="RFC5555">
            <front>
               <title>Mobile IPv6 Support for Dual Stack Hosts and
                  Routers</title>
               <author
                  fullname="H. Soliman"
                  initials="H."
                  role="editor"
                  surname="Soliman">
                  <organization>Elevate Technologies</organization>
               </author>
               <date
                  month="June"
                  year="2009" />
            </front>
            <seriesInfo
               name="RFC"
               value="5555" />
         </reference>


         <reference
            anchor="RFC5679">
            <front>
               <title>Locating IEEE 802.21 Mobility Services Using DNS</title>
               <author
                  fullname="G. Bajko"
                  initials="G."
                  surname="Bajko" />
               <date
                  month="December"
                  year="2009" />
            </front>
            <seriesInfo
               name="RFC"
               value="5679" />
         </reference>


         <reference
            anchor="RFC5766">
            <front>
               <title>Traversal Using Relays around NAT (TURN): Relay Extensions
                  to Session Traversal Utilities for NAT (STUN)</title>
               <author
                  fullname="R. Mahy"
                  initials="R."
                  surname="Mahy" />
               <author
                  fullname="P. Matthews"
                  initials="P."
                  surname="Matthews">
                  <organization>Alcatel-Lucent</organization>
               </author>
               <author
                  fullname="J. Rosenberg"
                  initials="J."
                  surname="Rosenberg">
                  <organization>jdrosen.net</organization>
               </author>
               <date
                  month="April"
                  year="2010" />
            </front>
            <seriesInfo
               name="RFC"
               value="5766" />
         </reference>


         <reference
            anchor="RFC5780">
            <front>
               <title>NAT Behavior Discovery Using Session Traversal Utilities
                  for NAT (STUN)</title>
               <author
                  fullname="D. MacDonald"
                  initials="D."
                  surname="MacDonald">
                  <organization>Skype</organization>
               </author>
               <author
                  fullname="B. Lowekamp"
                  initials="B."
                  surname="Lowekamp">
                  <organization>Skype</organization>
               </author>
               <date
                  month="May"
                  year="2010" />
            </front>
            <seriesInfo
               name="RFC"
               value="5780" />
         </reference>


         <reference
            anchor="RFC5804">
            <front>
               <title>A Protocol for Remotely Managing Sieve Scripts</title>
               <author
                  fullname="A. Melnikov"
                  initials="A."
                  role="editor"
                  surname="Melnikov">
                  <organization>Isode Limited</organization>
               </author>
               <author
                  fullname="T. Martin"
                  initials="T."
                  surname="Martin">
                  <organization>BeThereBeSquare, Inc.</organization>
               </author>
               <date
                  month="July"
                  year="2010" />
            </front>
            <seriesInfo
               name="RFC"
               value="5804" />
         </reference>


         <reference
            anchor="RFC5864">
            <front>
               <title>NS SRV Resource Records for AFS</title>
               <author
                  fullname="R. Allbery"
                  initials="R."
                  surname="Allbery">
                  <organization>Stanford University</organization>
               </author>
               <date
                  month="April"
                  year="2010" />
            </front>
            <seriesInfo
               name="RFC"
               value="5864" />
         </reference>


         <reference
            anchor="RFC5928">
            <front>
               <title>Traversal Using Relays around NAT (TURN) Resolution
                  Mechanism</title>
               <author
                  fullname="M. Petit-Huguenin"
                  initials="M."
                  surname="Petit-Huguenin" />
               <date
                  month="August"
                  year="2010" />
            </front>
            <seriesInfo
               name="RFC"
               value="5928" />
         </reference>


         <reference
            anchor="RFC6011">
            <front>
               <title>Session Initiation Protocol (SIP) User Agent
                  Configuration</title>
               <author
                  fullname="S. Lawrence"
                  initials="S."
                  role="editor"
                  surname="Lawrence">
                  <organization>Linden Research, Inc.</organization>
               </author>
               <author
                  fullname="J. Elwell"
                  initials="J."
                  surname="Elwell">
                  <organization>Siemens Enterprise Communications</organization>
               </author>
               <date
                  month="October"
                  year="2010" />
            </front>
            <seriesInfo
               name="RFC"
               value="6011" />
         </reference>

         <reference
            anchor="RFC6120">
            <front>
               <title>Extensible Messaging and Presence Protocol (XMPP):
                  Core</title>
               <author
                  fullname="P. Saint-Andre"
                  initials="P."
                  surname="Saint-Andre">
                  <organization>Cisco</organization>
               </author>
               <date
                  month="March"
                  year="2011" />
            </front>
            <seriesInfo
               name="RFC"
               value="6120" />
         </reference>

         <reference
            anchor="RFC6186">
            <front>
               <title>Use of SRV Records for Locating Email Submission/Access
                  Services</title>
               <author
                  fullname="C. Daboo"
                  initials="C."
                  surname="Daboo">
                  <organization>Apple Inc.</organization>
               </author>
               <date
                  month="March"
                  year="2011" />
            </front>
            <seriesInfo
               name="RFC"
               value="6186" />
         </reference>


      </references>



      <section
         title="Acknowledgements">
         <t>Thanks go to Bill Fenner, Tony Hansen, Peter Koch, Olaf Kolkman, and
            Andrew Sullivan for diligent review of the earlier drafts.</t>
      </section>
   </back>
</rfc>

PAFTECH AB 2003-20262026-04-23 14:22:29