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        !           143: <body>
        !           144: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           145: <table summary="layout" width="66%" border="0" cellpadding="0" cellspacing="0"><tr><td><table summary="layout" width="100%" border="0" cellpadding="2" cellspacing="1">
        !           146: <tr><td class="header">ISC-DHCP-REFERENCES</td><td class="header">D. Hankins</td></tr>
        !           147: <tr><td class="header">&nbsp;</td><td class="header">ISC</td></tr>
        !           148: <tr><td class="header">&nbsp;</td><td class="header">May 2007</td></tr>
        !           149: </table></td></tr></table>
        !           150: <h1><br />ISC DHCP References Collection</h1>
        !           151: 
        !           152: <h3>Copyright Notice</h3>
        !           153: 
        !           154: <p>Copyright (c) 2006-2007,2009 by Internet Systems Consortium, Inc.
        !           155:        ("ISC")
        !           156: </p>
        !           157: <p>Permission to use, copy, modify, and distribute this software for
        !           158:        any purpose with or without fee is hereby granted, provided that the
        !           159:        above copyright notice and this permission notice appear in all
        !           160:        copies.
        !           161: </p>
        !           162: <p>THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
        !           163:        WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
        !           164:        MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
        !           165:        ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
        !           166:        WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
        !           167:        ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
        !           168:        OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
        !           169: </p>
        !           170: <h3>Abstract</h3>
        !           171: 
        !           172: <p>This document describes a collection of Reference material that
        !           173:        ISC DHCP has been implemented to.
        !           174: </p><a name="toc"></a><br /><hr />
        !           175: <h3>Table of Contents</h3>
        !           176: <p class="toc">
        !           177: <a href="#anchor1">1.</a>&nbsp;
        !           178: Introduction<br />
        !           179: <br />
        !           180: <a href="#anchor2">2.</a>&nbsp;
        !           181: Definition: Reference Implementation<br />
        !           182: <br />
        !           183: <a href="#anchor3">3.</a>&nbsp;
        !           184: Low Layer References<br />
        !           185: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor4">3.1.</a>&nbsp;
        !           186: Ethernet Protocol References<br />
        !           187: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor5">3.2.</a>&nbsp;
        !           188: Token Ring Protocol References<br />
        !           189: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor6">3.3.</a>&nbsp;
        !           190: FDDI Protocol References<br />
        !           191: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor7">3.4.</a>&nbsp;
        !           192: Internet Protocol Version 4 References<br />
        !           193: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor8">3.5.</a>&nbsp;
        !           194: Unicast Datagram Protocol References<br />
        !           195: <br />
        !           196: <a href="#anchor9">4.</a>&nbsp;
        !           197: BOOTP Protocol References<br />
        !           198: <br />
        !           199: <a href="#anchor10">5.</a>&nbsp;
        !           200: DHCP Protocol References<br />
        !           201: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor11">5.1.</a>&nbsp;
        !           202: DHCPv4 Protocol<br />
        !           203: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor12">5.1.1.</a>&nbsp;
        !           204: Core Protocol References<br />
        !           205: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor13">5.2.</a>&nbsp;
        !           206: DHCPv6 Protocol References<br />
        !           207: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor14">5.3.</a>&nbsp;
        !           208: DHCP Option References<br />
        !           209: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor15">5.3.1.</a>&nbsp;
        !           210: Relay Agent Information Option Options<br />
        !           211: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor16">5.3.2.</a>&nbsp;
        !           212: Dynamic DNS Updates References<br />
        !           213: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor17">5.3.3.</a>&nbsp;
        !           214: Experimental: Failover References<br />
        !           215: &nbsp;&nbsp;&nbsp;&nbsp;<a href="#anchor18">5.4.</a>&nbsp;
        !           216: DHCP Procedures<br />
        !           217: <br />
        !           218: <a href="#rfc.references1">6.</a>&nbsp;
        !           219: References<br />
        !           220: <br />
        !           221: <a href="#rfc.authors">&#167;</a>&nbsp;
        !           222: Author's Address<br />
        !           223: </p>
        !           224: <br clear="all" />
        !           225: 
        !           226: <a name="anchor1"></a><br /><hr />
        !           227: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           228: <a name="rfc.section.1"></a><h3>1.&nbsp;
        !           229: Introduction</h3>
        !           230: 
        !           231: <p>As a little historical anecdote, ISC DHCP once packaged all the
        !           232:        relevant RFCs and standards documents along with the software
        !           233:        package.  Until one day when a voice was heard from one of the
        !           234:        many fine institutions that build and distribute this software...
        !           235:        they took issue with the IETF's copyright on the RFC's.  It
        !           236:        seems the IETF's copyrights don't allow modification of RFC's
        !           237:        (except for translation purposes).
        !           238: </p>
        !           239: <p>Our main purpose in providing the RFCs is to aid in
        !           240:        documentation, but since RFCs are now available widely from many
        !           241:        points of distribution on the Internet, there is no real need to
        !           242:        provide the documents themselves.  So, this document has been
        !           243:        created in their stead, to list the various IETF RFCs one might
        !           244:        want to read, and to comment on how well (or poorly) we have
        !           245:        managed to implement them.
        !           246: </p>
        !           247: <a name="anchor2"></a><br /><hr />
        !           248: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           249: <a name="rfc.section.2"></a><h3>2.&nbsp;
        !           250: Definition: Reference Implementation</h3>
        !           251: 
        !           252: <p>ISC DHCP, much like its other cousins in ISC software, is
        !           253:        self-described as a 'Reference Implementation.'  There has been
        !           254:        a great deal of confusion about this term.  Some people seem to
        !           255:        think that this term applies to any software that once passed
        !           256:        a piece of reference material on its way to market (but may do
        !           257:        quite a lot of things that aren't described in any reference, or
        !           258:        may choose to ignore the reference it saw entirely).  Other folks
        !           259:        get confused by the word 'reference' and understand that to mean
        !           260:        that there is some special status applied to the software - that
        !           261:        the software itself is the reference by which all other software
        !           262:        is measured.  Something along the lines of being "The DHCP
        !           263:        Protocol's Reference Clock," it is supposed.
        !           264: </p>
        !           265: <p>The truth is actually quite a lot simpler.  Reference
        !           266:        implementations are software packages which were written
        !           267:        to behave precisely as appears in reference material.  They
        !           268:        are written "to match reference."
        !           269: </p>
        !           270: <p>If the software has a behaviour that manifests itself
        !           271:        externally (whether it be something as simple as the 'wire
        !           272:        format' or something higher level, such as a complicated
        !           273:        behaviour that arises from multiple message exchanges), that
        !           274:        behaviour must be found in a reference document.
        !           275: </p>
        !           276: <p>Anything else is a bug, the only question is whether the
        !           277:        bug is in reference or software (failing to implement the
        !           278:        reference).
        !           279: </p>
        !           280: <p>This means:
        !           281: </p>
        !           282: <ul class="text">
        !           283: <li>To produce new externally-visible behaviour, one must first
        !           284:        provide a reference.
        !           285: </li>
        !           286: <li>Before changing externally visible behaviour to work around
        !           287:        simple incompatibilities in any other implementation, one must
        !           288:        first provide a reference.
        !           289: </li>
        !           290: </ul>
        !           291: <p>That is the lofty goal, at any rate.  It's well understood that,
        !           292:        especially because the ISC DHCP Software package has not always been
        !           293:        held to this standard (but not entirely due to it), there are many
        !           294:        non-referenced behaviours within ISC DHCP.
        !           295: </p>
        !           296: <p>The primary goal of reference implementation is to prove the
        !           297:        reference material.  If the reference material is good, then you
        !           298:        should be able to sit down and write a program that implements the
        !           299:        reference, to the word, and come to an implementation that
        !           300:        is distinguishable from others in the details, but not in the
        !           301:        facts of operating the protocol.  This means that there is no
        !           302:        need for 'special knowledge' to work around arcane problems that
        !           303:        were left undocumented.  No secret handshakes need to be learned
        !           304:        to be imparted with the necessary "real documentation".
        !           305: </p>
        !           306: <p>Also, by accepting only reference as the guidebook for ISC
        !           307:        DHCP's software implementation, anyone who can make an impact on
        !           308:        the color texture or form of that reference has a (somewhat
        !           309:        indirect) voice in ISC DHCP's software design.  As the IETF RFC's
        !           310:        have been selected as the source of reference, that means everyone
        !           311:        on the Internet with the will to participate has a say.
        !           312: </p>
        !           313: <a name="anchor3"></a><br /><hr />
        !           314: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           315: <a name="rfc.section.3"></a><h3>3.&nbsp;
        !           316: Low Layer References</h3>
        !           317: 
        !           318: <p>It may surprise you to realize that ISC DHCP implements 802.1
        !           319:        'Ethernet' framing, Token Ring, and FDDI.  In order to bridge the
        !           320:        gap there between these physical and DHCP layers, it must also
        !           321:        implement IP and UDP framing.
        !           322: </p>
        !           323: <p>The reason for this stems from Unix systems' handling of BSD
        !           324:        sockets (the general way one might engage in transmission of UDP
        !           325:        packets) on unconfigured interfaces, or even the handling of
        !           326:        broadcast addressing on configured interfaces.
        !           327: </p>
        !           328: <p>There are a few things that DHCP servers, relays, and clients all
        !           329:        need to do in order to speak the DHCP protocol in strict compliance
        !           330:        with <a class='info' href='#RFC2131'>RFC2131<span> (</span><span class='info'>Droms, R., &ldquo;Dynamic Host Configuration Protocol,&rdquo; March&nbsp;1997.</span><span>)</span></a> [RFC2131].
        !           331: </p>
        !           332: <ol class="text">
        !           333: <li>Transmit a UDP packet from IP:0.0.0.0 Ethernet:Self, destined to
        !           334:        IP:255.255.255.255 LinkLayer:Broadcast on an unconfigured (no IP
        !           335:        address yet) interface.
        !           336: </li>
        !           337: <li>Receive a UDP packet from IP:remote-system LinkLayer:remote-system,
        !           338:        destined to IP:255.255.255.255 LinkLayer:Broadcast, again on an
        !           339:        unconfigured interface.
        !           340: </li>
        !           341: <li>Transmit a UDP packet from IP:Self, Ethernet:Seelf, destined to
        !           342:        IP:remote-system LinkLayer:remote-system, without transmitting a
        !           343:        single ARP.
        !           344: </li>
        !           345: <li>And of course the simple case, a regular IP unicast that is
        !           346:        routed via the usual means (so it may be direct to a local system,
        !           347:        with ARP providing the glue, or it may be to a remote system via
        !           348:        one or more routers as normal).  In this case, the interfaces are
        !           349:        always configured.
        !           350: </li>
        !           351: </ol>
        !           352: <p>The above isn't as simple as it sounds on a regular BSD socket.
        !           353:        Many unix implementations will transmit broadcasts not to
        !           354:        255.255.255.255, but to x.y.z.255 (where x.y.z is the system's local
        !           355:        subnet).  Such packets are not received by several known DHCP client
        !           356:        implementations - and it's not their fault, <a class='info' href='#RFC2131'>RFC2131<span> (</span><span class='info'>Droms, R., &ldquo;Dynamic Host Configuration Protocol,&rdquo; March&nbsp;1997.</span><span>)</span></a> [RFC2131] very explicitly demands that these packets' IP
        !           357:        destination addresses be set to 255.255.255.255.
        !           358: </p>
        !           359: <p>Receiving packets sent to 255.255.255.255 isn't a problem on most
        !           360:        modern unixes...so long as the interface is configured.  When there
        !           361:        is no IPv4 address on the interface, things become much more murky.
        !           362: </p>
        !           363: <p>So, for this convoluted and unfortunate state of affairs in the
        !           364:        unix systems of the day ISC DHCP was manufactured, in order to do
        !           365:        what it needs not only to implement the reference but to interoperate
        !           366:        with other implementations, the software must create some form of
        !           367:        raw socket to operate on.
        !           368: </p>
        !           369: <p>What it actually does is create, for each interface detected on
        !           370:        the system, a Berkeley Packet Filter socket (or equivalent), and
        !           371:        program it with a filter that brings in only DHCP packets.  A
        !           372:        "fallback" UDP Berkeley socket is generally also created, a single
        !           373:        one no matter how many interfaces.  Should the software need to
        !           374:        transmit a contrived packet to the local network the packet is
        !           375:        formed piece by piece and transmitted via the BPF socket.  Hence
        !           376:        the need to implement many forms of Link Layer framing and above.
        !           377:        The software gets away with not having to implement IP routing
        !           378:        tables as well by simply utilizing the aforementioned 'fallback'
        !           379:        UDP socket when unicasting between two configured systems is the
        !           380:        need.
        !           381: </p>
        !           382: <p>Modern unixes have opened up some facilities that diminish how
        !           383:        much of this sort of nefarious kludgery is necessary, but have not
        !           384:        found the state of affairs absolutely absolved.  In particular,
        !           385:        one might now unicast without ARP by inserting an entry into the
        !           386:        ARP cache prior to transmitting.  Unconfigured interfaces remain
        !           387:        the sticking point, however...on virtually no modern unixes is
        !           388:        it possible to receive broadcast packets unless a local IPv4
        !           389:        address has been configured, unless it is done with raw sockets.
        !           390: </p>
        !           391: <a name="anchor4"></a><br /><hr />
        !           392: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           393: <a name="rfc.section.3.1"></a><h3>3.1.&nbsp;
        !           394: Ethernet Protocol References</h3>
        !           395: 
        !           396: <p>ISC DHCP Implements Ethernet Version 2 ("DIX"), which is a variant
        !           397:        of IEEE 802.2.  No good reference of this framing is known to exist
        !           398:        at this time, but it is vaguely described in <a class='info' href='#RFC0894'>RFC894<span> (</span><span class='info'>Hornig, C., &ldquo;Standard for the transmission of IP datagrams over Ethernet networks,&rdquo; April&nbsp;1984.</span><span>)</span></a> [RFC0894] (see the section titled "Packet format"), and
        !           399:        the following URL is also thought to be useful.
        !           400: </p>
        !           401: <p>http://en.wikipedia.org/wiki/DIX
        !           402: </p>
        !           403: <a name="anchor5"></a><br /><hr />
        !           404: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           405: <a name="rfc.section.3.2"></a><h3>3.2.&nbsp;
        !           406: Token Ring Protocol References</h3>
        !           407: 
        !           408: <p>IEEE 802.5 defines the Token Ring framing format used by ISC
        !           409:        DHCP.
        !           410: </p>
        !           411: <a name="anchor6"></a><br /><hr />
        !           412: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           413: <a name="rfc.section.3.3"></a><h3>3.3.&nbsp;
        !           414: FDDI Protocol References</h3>
        !           415: 
        !           416: <p><a class='info' href='#RFC1188'>RFC1188<span> (</span><span class='info'>Katz, D., &ldquo;Proposed Standard for the Transmission of IP Datagrams over FDDI Networks,&rdquo; October&nbsp;1990.</span><span>)</span></a> [RFC1188] is the most helpful
        !           417:        reference ISC DHCP has used to form FDDI packets.
        !           418: </p>
        !           419: <a name="anchor7"></a><br /><hr />
        !           420: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           421: <a name="rfc.section.3.4"></a><h3>3.4.&nbsp;
        !           422: Internet Protocol Version 4 References</h3>
        !           423: 
        !           424: <p><a class='info' href='#RFC0760'>RFC760<span> (</span><span class='info'>Postel, J., &ldquo;DoD standard Internet Protocol,&rdquo; January&nbsp;1980.</span><span>)</span></a> [RFC0760] fundamentally defines the
        !           425:        bare IPv4 protocol which ISC DHCP implements.
        !           426: </p>
        !           427: <a name="anchor8"></a><br /><hr />
        !           428: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           429: <a name="rfc.section.3.5"></a><h3>3.5.&nbsp;
        !           430: Unicast Datagram Protocol References</h3>
        !           431: 
        !           432: <p><a class='info' href='#RFC0768'>RFC768<span> (</span><span class='info'>Postel, J., &ldquo;User Datagram Protocol,&rdquo; August&nbsp;1980.</span><span>)</span></a> [RFC0768] defines the User Datagram
        !           433:        Protocol that ultimately carries the DHCP or BOOTP protocol.  The
        !           434:        destination DHCP server port is 67, the client port is 68.  Source
        !           435:        ports are irrelevant.
        !           436: </p>
        !           437: <a name="anchor9"></a><br /><hr />
        !           438: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           439: <a name="rfc.section.4"></a><h3>4.&nbsp;
        !           440: BOOTP Protocol References</h3>
        !           441: 
        !           442: <p>The DHCP Protocol is strange among protocols in that it is
        !           443:        grafted over the top of another protocol - BOOTP (but we don't
        !           444:        call it "DHCP over BOOTP" like we do, say "TCP over IP").  BOOTP
        !           445:        and DHCP share UDP packet formats - DHCP is merely a conventional
        !           446:        use of both BOOTP header fields and the trailing 'options' space.
        !           447: </p>
        !           448: <p>The ISC DHCP server supports BOOTP clients conforming to
        !           449:        <a class='info' href='#RFC0951'>RFC951<span> (</span><span class='info'>Croft, B. and J. Gilmore, &ldquo;Bootstrap Protocol,&rdquo; September&nbsp;1985.</span><span>)</span></a> [RFC0951] and <a class='info' href='#RFC1542'>RFC1542<span> (</span><span class='info'>Wimer, W., &ldquo;Clarifications and Extensions for the Bootstrap Protocol,&rdquo; October&nbsp;1993.</span><span>)</span></a> [RFC1542].
        !           450: </p>
        !           451: <a name="anchor10"></a><br /><hr />
        !           452: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           453: <a name="rfc.section.5"></a><h3>5.&nbsp;
        !           454: DHCP Protocol References</h3>
        !           455: 
        !           456: <a name="anchor11"></a><br /><hr />
        !           457: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           458: <a name="rfc.section.5.1"></a><h3>5.1.&nbsp;
        !           459: DHCPv4 Protocol</h3>
        !           460: 
        !           461: <p>"The DHCP[v4] Protocol" is not defined in a single document.  The
        !           462:        following collection of references of what ISC DHCP terms "The
        !           463:        DHCPv4 Protocol".
        !           464: </p>
        !           465: <a name="anchor12"></a><br /><hr />
        !           466: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           467: <a name="rfc.section.5.1.1"></a><h3>5.1.1.&nbsp;
        !           468: Core Protocol References</h3>
        !           469: 
        !           470: <p><a class='info' href='#RFC2131'>RFC2131<span> (</span><span class='info'>Droms, R., &ldquo;Dynamic Host Configuration Protocol,&rdquo; March&nbsp;1997.</span><span>)</span></a> [RFC2131] defines the protocol format
        !           471:        and procedures.  ISC DHCP is not known to diverge from this document
        !           472:        in any way.  There are, however, a few points on which different
        !           473:        implementations have arisen out of vagueries in the document.
        !           474:        DHCP Clients exist which, at one time, present themselves as using
        !           475:        a Client Identifier Option which is equal to the client's hardware
        !           476:        address.  Later, the client transmits DHCP packets with no Client
        !           477:        Identifier Option present - essentially identifying themselves using
        !           478:        the hardware address.  Some DHCP Servers have been developed which
        !           479:        identify this client as a single client.  ISC has interpreted
        !           480:        RFC2131 to indicate that these clients must be treated as two
        !           481:        separate entities (and hence two, separate addresses).  Client
        !           482:        behaviour (Embedded Windows products) has developed that relies on
        !           483:        the former implementation, and hence is incompatible with the
        !           484:        latter.  Also, RFC2131 demands explicitly that some header fields
        !           485:        be zeroed upon certain message types.  The ISC DHCP Server instead
        !           486:        copies many of these fields from the packet received from the client
        !           487:        or relay, which may not be zero.  It is not known if there is a good
        !           488:        reason for this that has not been documented.
        !           489: </p>
        !           490: <p><a class='info' href='#RFC2132'>RFC2132<span> (</span><span class='info'>Alexander, S. and R. Droms, &ldquo;DHCP Options and BOOTP Vendor Extensions,&rdquo; March&nbsp;1997.</span><span>)</span></a> [RFC2132] defines the initial set of
        !           491:        DHCP Options and provides a great deal of guidance on how to go about
        !           492:        formatting and processing options.  The document unfortunately
        !           493:        waffles to a great extent about the NULL termination of DHCP Options,
        !           494:        and some DHCP Clients (Windows 95) have been implemented that rely
        !           495:        upon DHCP Options containing text strings to be NULL-terminated (or
        !           496:        else they crash).  So, ISC DHCP detects if clients null-terminate the
        !           497:        host-name option and, if so, null terminates any text options it
        !           498:        transmits to the client.  It also removes NULL termination from any
        !           499:        known text option it receives prior to any other processing.
        !           500: </p>
        !           501: <a name="anchor13"></a><br /><hr />
        !           502: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           503: <a name="rfc.section.5.2"></a><h3>5.2.&nbsp;
        !           504: DHCPv6 Protocol References</h3>
        !           505: 
        !           506: <p>For now there is only one document that specifies the DHCPv6
        !           507:        protocol (there have been no updates yet), <a class='info' href='#RFC3315'>RFC3315<span> (</span><span class='info'>Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, &ldquo;Dynamic Host Configuration Protocol for IPv6 (DHCPv6),&rdquo; July&nbsp;2003.</span><span>)</span></a> [RFC3315].
        !           508: </p>
        !           509: <p>Support for DHCPv6 was added first in version 4.0.0.  The server
        !           510:        and client support only IA_NA.  While the server does support multiple
        !           511:        IA_NAs within one packet from the client, our client only supports
        !           512:        sending one.  There is no relay support.
        !           513: </p>
        !           514: <p>DHCPv6 introduces some new and uncomfortable ideas to the common
        !           515:        software library.
        !           516: </p>
        !           517: <ol class="text">
        !           518: <li>Options of zero length are normal in DHCPv6.  Currently, all
        !           519:          ISC DHCP software treats zero-length options as errors.
        !           520: </li>
        !           521: <li>Options sometimes may appear multiple times.  The common
        !           522:          library used to treat all appearance of multiple options as
        !           523:          specified in RFC2131 - to be concatenated.  DHCPv6 options
        !           524:          may sometimes appear multiple times (such as with IA_NA or
        !           525:          IAADDR), but often must not.
        !           526: </li>
        !           527: <li>The same option space appears in DHCPv6 packets multiple times.
        !           528:          If the packet was got via a relay, then the client's packet is
        !           529:          stored to an option within the relay's packet...if there were two
        !           530:          relays, this recurses.  At each of these steps, the root "DHCPv6
        !           531:          option space" is used.  Further, a client packet may contain an
        !           532:          IA_NA, which may contain an IAADDR - but really, in an abstract
        !           533:          sense, this is again re-encapsulation of the DHCPv6 option space
        !           534:          beneath options it also contains.
        !           535: </li>
        !           536: </ol>
        !           537: <p>Precisely how to correctly support the above conundrums has not
        !           538:        quite yet been settled, so support is incomplete.
        !           539: </p>
        !           540: <a name="anchor14"></a><br /><hr />
        !           541: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           542: <a name="rfc.section.5.3"></a><h3>5.3.&nbsp;
        !           543: DHCP Option References</h3>
        !           544: 
        !           545: <p><a class='info' href='#RFC2241'>RFC2241<span> (</span><span class='info'>Provan, D., &ldquo;DHCP Options for Novell Directory Services,&rdquo; November&nbsp;1997.</span><span>)</span></a> [RFC2241] defines options for
        !           546:        Novell Directory Services.
        !           547: </p>
        !           548: <p><a class='info' href='#RFC2242'>RFC2242<span> (</span><span class='info'>Droms, R. and K. Fong, &ldquo;NetWare/IP Domain Name and Information,&rdquo; November&nbsp;1997.</span><span>)</span></a> [RFC2242] defines an encapsulated
        !           549:        option space for NWIP configuration.
        !           550: </p>
        !           551: <p><a class='info' href='#RFC2485'>RFC2485<span> (</span><span class='info'>Drach, S., &ldquo;DHCP Option for The Open Group&apos;s User Authentication Protocol,&rdquo; January&nbsp;1999.</span><span>)</span></a> [RFC2485] defines the Open Group's
        !           552:        UAP option.
        !           553: </p>
        !           554: <p><a class='info' href='#RFC2610'>RFC2610<span> (</span><span class='info'>Perkins, C. and E. Guttman, &ldquo;DHCP Options for Service Location Protocol,&rdquo; June&nbsp;1999.</span><span>)</span></a> [RFC2610] defines options for
        !           555:        the Service Location Protocol (SLP).
        !           556: </p>
        !           557: <p><a class='info' href='#RFC2937'>RFC2937<span> (</span><span class='info'>Smith, C., &ldquo;The Name Service Search Option for DHCP,&rdquo; September&nbsp;2000.</span><span>)</span></a> [RFC2937] defines the Name Service
        !           558:        Search Option (not to be confused with the domain-search option).
        !           559:        The Name Service Search Option allows eg nsswitch.conf to be
        !           560:        reconfigured via dhcp.  The ISC DHCP server implements this option,
        !           561:        and the ISC DHCP client is compatible...but does not by default
        !           562:        install this option's value.  One would need to make their relevant
        !           563:        dhclient-script process this option in a way that is suitable for
        !           564:        the system.
        !           565: </p>
        !           566: <p><a class='info' href='#RFC3004'>RFC3004<span> (</span><span class='info'>Stump, G., Droms, R., Gu, Y., Vyaghrapuri, R., Demirtjis, A., Beser, B., and J. Privat, &ldquo;The User Class Option for DHCP,&rdquo; November&nbsp;2000.</span><span>)</span></a> [RFC3004] defines the User-Class
        !           567:        option.  Note carefully that ISC DHCP currently does not implement
        !           568:        to this reference, but has (inexplicably) selected an incompatible
        !           569:        format: a plain text string.
        !           570: </p>
        !           571: <p><a class='info' href='#RFC3011'>RFC3011<span> (</span><span class='info'>Waters, G., &ldquo;The IPv4 Subnet Selection Option for DHCP,&rdquo; November&nbsp;2000.</span><span>)</span></a> [RFC3011] defines the Subnet-Selection
        !           572:        plain DHCPv4 option.  Do not confuse this option with the relay agent
        !           573:        "link selection" sub-option, although their behaviour is similar.
        !           574: </p>
        !           575: <p><a class='info' href='#RFC3319'>RFC3319<span> (</span><span class='info'>Schulzrinne, H. and B. Volz, &ldquo;Dynamic Host Configuration Protocol (DHCPv6) Options for Session Initiation Protocol (SIP) Servers,&rdquo; July&nbsp;2003.</span><span>)</span></a> [RFC3319] defines the SIP server
        !           576:        options for DHCPv6.
        !           577: </p>
        !           578: <p><a class='info' href='#RFC3396'>RFC3396<span> (</span><span class='info'>Lemon, T. and S. Cheshire, &ldquo;Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4),&rdquo; November&nbsp;2002.</span><span>)</span></a> [RFC3396] documents both how long
        !           579:        options may be encoded in DHCPv4 packets, and also how multiple
        !           580:        instances of the same option code within a DHCPv4 packet will be
        !           581:        decoded by receivers.
        !           582: </p>
        !           583: <p><a class='info' href='#RFC3397'>RFC3397<span> (</span><span class='info'>Aboba, B. and S. Cheshire, &ldquo;Dynamic Host Configuration Protocol (DHCP) Domain Search Option,&rdquo; November&nbsp;2002.</span><span>)</span></a> [RFC3397] documents the Domain-Search
        !           584:        Option, which allows the configuration of the /etc/resolv.conf
        !           585:        'search' parameter in a way that is <a class='info' href='#RFC1035'>RFC1035<span> (</span><span class='info'>Mockapetris, P., &ldquo;Domain names - implementation and specification,&rdquo; November&nbsp;1987.</span><span>)</span></a> [RFC1035] wire format compatible (in fact, it uses the RFC1035 wire
        !           586:        format).  ISC DHCP has both client and server support, and supports
        !           587:        RFC1035 name compression.
        !           588: </p>
        !           589: <p><a class='info' href='#RFC3646'>RFC3646<span> (</span><span class='info'>Droms, R., &ldquo;DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6),&rdquo; December&nbsp;2003.</span><span>)</span></a> [RFC3646] documents the DHCPv6
        !           590:        name-servers and domain-search options.
        !           591: </p>
        !           592: <p><a class='info' href='#RFC3633'>RFC3633<span> (</span><span class='info'>Troan, O. and R. Droms, &ldquo;IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6,&rdquo; December&nbsp;2003.</span><span>)</span></a> [RFC3633] documents the Identity
        !           593:        Association Prefix Delegation, which is included here for protocol
        !           594:        wire reference, but which is not supported by ISC DHCP.
        !           595: </p>
        !           596: <p><a class='info' href='#RFC3679'>RFC3679<span> (</span><span class='info'>Droms, R., &ldquo;Unused Dynamic Host Configuration Protocol (DHCP) Option Codes,&rdquo; January&nbsp;2004.</span><span>)</span></a> [RFC3679] documents a number of
        !           597:        options that were documented earlier in history, but were not
        !           598:        made use of.
        !           599: </p>
        !           600: <p><a class='info' href='#RFC3898'>RFC3898<span> (</span><span class='info'>Kalusivalingam, V., &ldquo;Network Information Service (NIS) Configuration Options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6),&rdquo; October&nbsp;2004.</span><span>)</span></a> [RFC3898] documents four NIS options
        !           601:        for delivering NIS servers and domain information in DHCPv6.
        !           602: </p>
        !           603: <p><a class='info' href='#RFC3925'>RFC3925<span> (</span><span class='info'>Littlefield, J., &ldquo;Vendor-Identifying Vendor Options for Dynamic Host Configuration Protocol version 4 (DHCPv4),&rdquo; October&nbsp;2004.</span><span>)</span></a> [RFC3925] documents a pair of
        !           604:        Enterprise-ID delimited option spaces for vendors to use in order
        !           605:        to inform servers of their "vendor class" (sort of like 'uname'
        !           606:        or 'who and what am I'), and a means to deliver vendor-specific
        !           607:        and vendor-documented option codes and values.
        !           608: </p>
        !           609: <p><a class='info' href='#RFC3942'>RFC3942<span> (</span><span class='info'>Volz, B., &ldquo;Reclassifying Dynamic Host Configuration Protocol version 4 (DHCPv4) Options,&rdquo; November&nbsp;2004.</span><span>)</span></a> [RFC3942] redefined the 'site local'
        !           610:        option space.
        !           611: </p>
        !           612: <p><a class='info' href='#RFC4075'>RFC4075<span> (</span><span class='info'>Kalusivalingam, V., &ldquo;Simple Network Time Protocol (SNTP) Configuration Option for DHCPv6,&rdquo; May&nbsp;2005.</span><span>)</span></a> [RFC4075] defines the DHCPv6 SNTP
        !           613:        Servers option.
        !           614: </p>
        !           615: <p><a class='info' href='#RFC4242'>RFC4242<span> (</span><span class='info'>Venaas, S., Chown, T., and B. Volz, &ldquo;Information Refresh Time Option for Dynamic Host Configuration Protocol for IPv6 (DHCPv6),&rdquo; November&nbsp;2005.</span><span>)</span></a> [RFC4242] defines the Information
        !           616:        Refresh Time option, which advises DHCPv6 Information-Request
        !           617:        clients to return for updated information.
        !           618: </p>
        !           619: <p><a class='info' href='#RFC4280'>RFC4280<span> (</span><span class='info'>Chowdhury, K., Yegani, P., and L. Madour, &ldquo;Dynamic Host Configuration Protocol (DHCP) Options for Broadcast and Multicast Control Servers,&rdquo; November&nbsp;2005.</span><span>)</span></a> [RFC4280] defines two BCMS server
        !           620:        options.
        !           621: </p>
        !           622: <p><a class='info' href='#RFC4388'>RFC4388<span> (</span><span class='info'>Woundy, R. and K. Kinnear, &ldquo;Dynamic Host Configuration Protocol (DHCP) Leasequery,&rdquo; February&nbsp;2006.</span><span>)</span></a> [RFC4388] defined the DHCPv4
        !           623:        LEASEQUERY message type and a number of suitable response messages,
        !           624:        for the purpose of sharing information about DHCP served addresses
        !           625:        and clients.
        !           626: </p>
        !           627: <p><a class='info' href='#RFC4580'>RFC4580<span> (</span><span class='info'>Volz, B., &ldquo;Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Relay Agent Subscriber-ID Option,&rdquo; June&nbsp;2006.</span><span>)</span></a> [RFC4580] defines a DHCPv6
        !           628:        subscriber-id option, which is similar in principle to the DHCPv4
        !           629:        relay agent option of the same name.
        !           630: </p>
        !           631: <p><a class='info' href='#RFC4649'>RFC4649<span> (</span><span class='info'>Volz, B., &ldquo;Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Relay Agent Remote-ID Option,&rdquo; August&nbsp;2006.</span><span>)</span></a> [RFC4649] defines a DHCPv6 remote-id
        !           632:        option, which is similar in principle to the DHCPv4 relay agent
        !           633:        remote-id.
        !           634: </p>
        !           635: <a name="anchor15"></a><br /><hr />
        !           636: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           637: <a name="rfc.section.5.3.1"></a><h3>5.3.1.&nbsp;
        !           638: Relay Agent Information Option Options</h3>
        !           639: 
        !           640: <p><a class='info' href='#RFC3046'>RFC3046<span> (</span><span class='info'>Patrick, M., &ldquo;DHCP Relay Agent Information Option,&rdquo; January&nbsp;2001.</span><span>)</span></a> [RFC3046] defines the Relay Agent
        !           641:          Information Option and provides a number of sub-option
        !           642:          definitions.
        !           643: </p>
        !           644: <p><a class='info' href='#RFC3256'>RFC3256<span> (</span><span class='info'>Jones, D. and R. Woundy, &ldquo;The DOCSIS (Data-Over-Cable Service Interface Specifications) Device Class DHCP (Dynamic Host Configuration Protocol) Relay Agent Information Sub-option,&rdquo; April&nbsp;2002.</span><span>)</span></a> [RFC3256] defines the DOCSIS Device
        !           645:          Class sub-option.
        !           646: </p>
        !           647: <p><a class='info' href='#RFC3527'>RFC3527<span> (</span><span class='info'>Kinnear, K., Stapp, M., Johnson, R., and J. Kumarasamy, &ldquo;Link Selection sub-option for the Relay Agent Information Option for DHCPv4,&rdquo; April&nbsp;2003.</span><span>)</span></a> [RFC3527] defines the Link Selection
        !           648:          sub-option.
        !           649: </p>
        !           650: <a name="anchor16"></a><br /><hr />
        !           651: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           652: <a name="rfc.section.5.3.2"></a><h3>5.3.2.&nbsp;
        !           653: Dynamic DNS Updates References</h3>
        !           654: 
        !           655: <p>The collection of documents that describe the standards-based
        !           656:          method to update dns names of DHCP clients starts most easily
        !           657:          with <a class='info' href='#RFC4703'>RFC4703<span> (</span><span class='info'>Stapp, M. and B. Volz, &ldquo;Resolution of Fully Qualified Domain Name (FQDN) Conflicts among Dynamic Host Configuration Protocol (DHCP) Clients,&rdquo; October&nbsp;2006.</span><span>)</span></a> [RFC4703] to define the overall
        !           658:          architecture, travels through RFCs <a class='info' href='#RFC4702'>4702<span> (</span><span class='info'>Stapp, M., Volz, B., and Y. Rekhter, &ldquo;The Dynamic Host Configuration Protocol (DHCP) Client Fully Qualified Domain Name (FQDN) Option,&rdquo; October&nbsp;2006.</span><span>)</span></a> [RFC4702]
        !           659:          and <a class='info' href='#RFC4704'>4704<span> (</span><span class='info'>Volz, B., &ldquo;The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Client Fully Qualified Domain Name (FQDN) Option,&rdquo; October&nbsp;2006.</span><span>)</span></a> [RFC4704] to describe the DHCPv4 and
        !           660:          DHCPv6 FQDN options (to carry the client name), and ends up at
        !           661:          <a class='info' href='#RFC4701'>RFC4701<span> (</span><span class='info'>Stapp, M., Lemon, T., and A. Gustafsson, &ldquo;A DNS Resource Record (RR) for Encoding Dynamic Host Configuration Protocol (DHCP) Information (DHCID RR),&rdquo; October&nbsp;2006.</span><span>)</span></a> [RFC4701] which describes the DHCID
        !           662:          RR used in DNS to perform a kind of atomic locking.
        !           663: </p>
        !           664: <p>ISC DHCP adopted early versions of these documents, and has not
        !           665:          yet synchronized with the final standards versions.
        !           666: </p>
        !           667: <p>For RFCs 4702 and 4704, the 'N' bit is not yet supported.  The
        !           668:          result is that it is always set zero, and is ignored if set.
        !           669: </p>
        !           670: <p>For RFC4701, which is used to match client identities with names
        !           671:          in the DNS as part of name conflict resolution.  Note that ISC DHCP's
        !           672:          implementation of DHCIDs vary wildly from this specification.
        !           673:          First, ISC DHCP uses a TXT record in which the contents are stored
        !           674:          in hexadecimal.  Second, there is a flaw in the selection of the
        !           675:          'Identifier Type', which results in a completely different value
        !           676:          being selected than was defined in an older revision of this
        !           677:          document...also this field is one byte prior to hexadecimal
        !           678:          encoding rather than two.  Third, ISC DHCP does not use a digest
        !           679:          type code.  Rather, all values for such TXT records are reached
        !           680:          via an MD5 sum.  In short, nothing is compatible, but the
        !           681:          principle of the TXT record is the same as the standard DHCID
        !           682:          record.  However, for DHCPv6 FQDN, we do use DHCID type code '2',
        !           683:          as no other value really makes sense in our context.
        !           684: </p>
        !           685: <a name="anchor17"></a><br /><hr />
        !           686: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           687: <a name="rfc.section.5.3.3"></a><h3>5.3.3.&nbsp;
        !           688: Experimental: Failover References</h3>
        !           689: 
        !           690: <p>The Failover Protocol defines a means by which two DHCP Servers
        !           691:          can share all the relevant information about leases granted to
        !           692:          DHCP clients on given networks, so that one of the two servers may
        !           693:          fail and be survived by a server that can act responsibly.
        !           694: </p>
        !           695: <p>Unfortunately it has been quite some years since the last time
        !           696:          this document was edited, and the authors no longer show any
        !           697:          interest in fielding comments or improving the document.
        !           698: </p>
        !           699: <p>The status of this protocol is very unsure, but ISC's
        !           700:          implementation of it has proven stable and suitable for use in
        !           701:          sizable production environments.
        !           702: </p>
        !           703: <p><a class='info' href='#draft-failover'>draft-ietf-dhc-failover-12.txt<span> (</span><span class='info'>Droms, R., &ldquo;DHCP Failover Protocol,&rdquo; March&nbsp;2003.</span><span>)</span></a> [draft&#8209;failover]
        !           704:          describes the Failover Protocol.  In addition to what is described
        !           705:          in this document, ISC DHCP has elected to make some experimental
        !           706:          changes that may be revoked in a future version of ISC DHCP (if the
        !           707:          draft authors do not adopt the new behaviour).  Specifically, ISC
        !           708:          DHCP's POOLREQ behaviour differs substantially from what is
        !           709:          documented in the draft, and the server also implements a form of
        !           710:          'MAC Address Affinity' which is not described in the failover
        !           711:          document.  The full nature of these changes have been described on
        !           712:          the IETF DHC WG mailing list (which has archives), and also in ISC
        !           713:          DHCP's manual pages.  Also note that although this document
        !           714:          references a RECOVER-WAIT state, it does not document a protocol
        !           715:          number assignment for this state.  As a consequence, ISC DHCP has
        !           716:          elected to use the value 254.
        !           717: </p>
        !           718: <p><a class='info' href='#RFC3074'>RFC3074<span> (</span><span class='info'>Volz, B., Gonczi, S., Lemon, T., and R. Stevens, &ldquo;DHC Load Balancing Algorithm,&rdquo; February&nbsp;2001.</span><span>)</span></a> [RFC3074] describes the Load Balancing
        !           719:          Algorithm (LBA) that ISC DHCP uses in concert with the Failover
        !           720:          protocol.  Note that versions 3.0.* are known to misimplement the
        !           721:          hash algorithm (it will only use the low 4 bits of every byte of
        !           722:          the hash bucket array).
        !           723: </p>
        !           724: <a name="anchor18"></a><br /><hr />
        !           725: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           726: <a name="rfc.section.5.4"></a><h3>5.4.&nbsp;
        !           727: DHCP Procedures</h3>
        !           728: 
        !           729: <p><a class='info' href='#RFC2939'>RFC2939<span> (</span><span class='info'>Droms, R., &ldquo;Procedures and IANA Guidelines for Definition of New DHCP Options and Message Types,&rdquo; September&nbsp;2000.</span><span>)</span></a> [RFC2939] explains how to go about
        !           730:        obtaining a new DHCP Option code assignment.
        !           731: </p>
        !           732: <a name="rfc.references1"></a><br /><hr />
        !           733: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           734: <h3>6.&nbsp;References</h3>
        !           735: <table width="99%" border="0">
        !           736: <tr><td class="author-text" valign="top"><a name="RFC0760">[RFC0760]</a></td>
        !           737: <td class="author-text">Postel, J., &ldquo;<a href="http://tools.ietf.org/html/rfc760">DoD standard Internet Protocol</a>,&rdquo; RFC&nbsp;760, January&nbsp;1980 (<a href="ftp://ftp.isi.edu/in-notes/rfc760.txt">TXT</a>).</td></tr>
        !           738: <tr><td class="author-text" valign="top"><a name="RFC0768">[RFC0768]</a></td>
        !           739: <td class="author-text">Postel, J., &ldquo;<a href="http://tools.ietf.org/html/rfc768">User Datagram Protocol</a>,&rdquo; STD&nbsp;6, RFC&nbsp;768, August&nbsp;1980 (<a href="ftp://ftp.isi.edu/in-notes/rfc768.txt">TXT</a>).</td></tr>
        !           740: <tr><td class="author-text" valign="top"><a name="RFC0894">[RFC0894]</a></td>
        !           741: <td class="author-text">Hornig, C., &ldquo;<a href="http://tools.ietf.org/html/rfc894">Standard for the transmission of IP datagrams over Ethernet networks</a>,&rdquo; STD&nbsp;41, RFC&nbsp;894, April&nbsp;1984 (<a href="ftp://ftp.isi.edu/in-notes/rfc894.txt">TXT</a>).</td></tr>
        !           742: <tr><td class="author-text" valign="top"><a name="RFC0951">[RFC0951]</a></td>
        !           743: <td class="author-text">Croft, B. and J. Gilmore, &ldquo;<a href="http://tools.ietf.org/html/rfc951">Bootstrap Protocol</a>,&rdquo; RFC&nbsp;951, September&nbsp;1985 (<a href="ftp://ftp.isi.edu/in-notes/rfc951.txt">TXT</a>).</td></tr>
        !           744: <tr><td class="author-text" valign="top"><a name="RFC1035">[RFC1035]</a></td>
        !           745: <td class="author-text">Mockapetris, P., &ldquo;<a href="http://tools.ietf.org/html/rfc1035">Domain names - implementation and specification</a>,&rdquo; STD&nbsp;13, RFC&nbsp;1035, November&nbsp;1987 (<a href="ftp://ftp.isi.edu/in-notes/rfc1035.txt">TXT</a>).</td></tr>
        !           746: <tr><td class="author-text" valign="top"><a name="RFC1188">[RFC1188]</a></td>
        !           747: <td class="author-text"><a href="mailto:dkatz@merit.edu">Katz, D.</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc1188">Proposed Standard for the Transmission of IP Datagrams over FDDI Networks</a>,&rdquo; RFC&nbsp;1188, October&nbsp;1990 (<a href="ftp://ftp.isi.edu/in-notes/rfc1188.txt">TXT</a>).</td></tr>
        !           748: <tr><td class="author-text" valign="top"><a name="RFC1542">[RFC1542]</a></td>
        !           749: <td class="author-text"><a href="mailto:Walter.Wimer@CMU.EDU">Wimer, W.</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc1542">Clarifications and Extensions for the Bootstrap Protocol</a>,&rdquo; RFC&nbsp;1542, October&nbsp;1993 (<a href="ftp://ftp.isi.edu/in-notes/rfc1542.txt">TXT</a>).</td></tr>
        !           750: <tr><td class="author-text" valign="top"><a name="RFC2131">[RFC2131]</a></td>
        !           751: <td class="author-text"><a href="mailto:droms@bucknell.edu">Droms, R.</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc2131">Dynamic Host Configuration Protocol</a>,&rdquo; RFC&nbsp;2131, March&nbsp;1997 (<a href="ftp://ftp.isi.edu/in-notes/rfc2131.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2131.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2131.xml">XML</a>).</td></tr>
        !           752: <tr><td class="author-text" valign="top"><a name="RFC2132">[RFC2132]</a></td>
        !           753: <td class="author-text"><a href="mailto:sca@engr.sgi.com">Alexander, S.</a> and <a href="mailto:droms@bucknell.edu">R. Droms</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc2132">DHCP Options and BOOTP Vendor Extensions</a>,&rdquo; RFC&nbsp;2132, March&nbsp;1997 (<a href="ftp://ftp.isi.edu/in-notes/rfc2132.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2132.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2132.xml">XML</a>).</td></tr>
        !           754: <tr><td class="author-text" valign="top"><a name="RFC2241">[RFC2241]</a></td>
        !           755: <td class="author-text"><a href="mailto:donp@Novell.Com">Provan, D.</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc2241">DHCP Options for Novell Directory Services</a>,&rdquo; RFC&nbsp;2241, November&nbsp;1997 (<a href="ftp://ftp.isi.edu/in-notes/rfc2241.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2241.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2241.xml">XML</a>).</td></tr>
        !           756: <tr><td class="author-text" valign="top"><a name="RFC2242">[RFC2242]</a></td>
        !           757: <td class="author-text"><a href="mailto:droms@bucknell.edu">Droms, R.</a> and <a href="mailto:kfong@novell.com">K. Fong</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc2242">NetWare/IP Domain Name and Information</a>,&rdquo; RFC&nbsp;2242, November&nbsp;1997 (<a href="ftp://ftp.isi.edu/in-notes/rfc2242.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2242.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2242.xml">XML</a>).</td></tr>
        !           758: <tr><td class="author-text" valign="top"><a name="RFC2485">[RFC2485]</a></td>
        !           759: <td class="author-text"><a href="mailto:drach@sun.com">Drach, S.</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc2485">DHCP Option for The Open Group&#039;s User Authentication Protocol</a>,&rdquo; RFC&nbsp;2485, January&nbsp;1999 (<a href="ftp://ftp.isi.edu/in-notes/rfc2485.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2485.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2485.xml">XML</a>).</td></tr>
        !           760: <tr><td class="author-text" valign="top"><a name="RFC2610">[RFC2610]</a></td>
        !           761: <td class="author-text"><a href="mailto:Charles.Perkins@Sun.Com">Perkins, C.</a> and <a href="mailto:Erik.Guttman@Sun.Com">E. Guttman</a>, &ldquo;<a href="http://tools.ietf.org/html/rfc2610">DHCP Options for Service Location Protocol</a>,&rdquo; RFC&nbsp;2610, June&nbsp;1999 (<a href="ftp://ftp.isi.edu/in-notes/rfc2610.txt">TXT</a>).</td></tr>
        !           762: <tr><td class="author-text" valign="top"><a name="RFC2937">[RFC2937]</a></td>
        !           763: <td class="author-text">Smith, C., &ldquo;<a href="http://tools.ietf.org/html/rfc2937">The Name Service Search Option for DHCP</a>,&rdquo; RFC&nbsp;2937, September&nbsp;2000 (<a href="ftp://ftp.isi.edu/in-notes/rfc2937.txt">TXT</a>).</td></tr>
        !           764: <tr><td class="author-text" valign="top"><a name="RFC2939">[RFC2939]</a></td>
        !           765: <td class="author-text">Droms, R., &ldquo;<a href="http://tools.ietf.org/html/rfc2939">Procedures and IANA Guidelines for Definition of New DHCP Options and Message Types</a>,&rdquo; BCP&nbsp;43, RFC&nbsp;2939, September&nbsp;2000 (<a href="ftp://ftp.isi.edu/in-notes/rfc2939.txt">TXT</a>).</td></tr>
        !           766: <tr><td class="author-text" valign="top"><a name="RFC3004">[RFC3004]</a></td>
        !           767: <td class="author-text">Stump, G., Droms, R., Gu, Y., Vyaghrapuri, R., Demirtjis, A., Beser, B., and J. Privat, &ldquo;<a href="http://tools.ietf.org/html/rfc3004">The User Class Option for DHCP</a>,&rdquo; RFC&nbsp;3004, November&nbsp;2000 (<a href="ftp://ftp.isi.edu/in-notes/rfc3004.txt">TXT</a>).</td></tr>
        !           768: <tr><td class="author-text" valign="top"><a name="RFC3011">[RFC3011]</a></td>
        !           769: <td class="author-text">Waters, G., &ldquo;<a href="http://tools.ietf.org/html/rfc3011">The IPv4 Subnet Selection Option for DHCP</a>,&rdquo; RFC&nbsp;3011, November&nbsp;2000 (<a href="ftp://ftp.isi.edu/in-notes/rfc3011.txt">TXT</a>).</td></tr>
        !           770: <tr><td class="author-text" valign="top"><a name="RFC3046">[RFC3046]</a></td>
        !           771: <td class="author-text">Patrick, M., &ldquo;<a href="http://tools.ietf.org/html/rfc3046">DHCP Relay Agent Information Option</a>,&rdquo; RFC&nbsp;3046, January&nbsp;2001 (<a href="ftp://ftp.isi.edu/in-notes/rfc3046.txt">TXT</a>).</td></tr>
        !           772: <tr><td class="author-text" valign="top"><a name="RFC3074">[RFC3074]</a></td>
        !           773: <td class="author-text">Volz, B., Gonczi, S., Lemon, T., and R. Stevens, &ldquo;<a href="http://tools.ietf.org/html/rfc3074">DHC Load Balancing Algorithm</a>,&rdquo; RFC&nbsp;3074, February&nbsp;2001 (<a href="ftp://ftp.isi.edu/in-notes/rfc3074.txt">TXT</a>).</td></tr>
        !           774: <tr><td class="author-text" valign="top"><a name="RFC3256">[RFC3256]</a></td>
        !           775: <td class="author-text">Jones, D. and R. Woundy, &ldquo;<a href="http://tools.ietf.org/html/rfc3256">The DOCSIS (Data-Over-Cable Service Interface Specifications) Device Class DHCP (Dynamic Host Configuration Protocol) Relay Agent Information Sub-option</a>,&rdquo; RFC&nbsp;3256, April&nbsp;2002 (<a href="ftp://ftp.isi.edu/in-notes/rfc3256.txt">TXT</a>).</td></tr>
        !           776: <tr><td class="author-text" valign="top"><a name="RFC3315">[RFC3315]</a></td>
        !           777: <td class="author-text">Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, &ldquo;<a href="http://tools.ietf.org/html/rfc3315">Dynamic Host Configuration Protocol for IPv6 (DHCPv6)</a>,&rdquo; RFC&nbsp;3315, July&nbsp;2003 (<a href="ftp://ftp.isi.edu/in-notes/rfc3315.txt">TXT</a>).</td></tr>
        !           778: <tr><td class="author-text" valign="top"><a name="RFC3319">[RFC3319]</a></td>
        !           779: <td class="author-text">Schulzrinne, H. and B. Volz, &ldquo;<a href="http://tools.ietf.org/html/rfc3319">Dynamic Host Configuration Protocol (DHCPv6) Options for Session Initiation Protocol (SIP) Servers</a>,&rdquo; RFC&nbsp;3319, July&nbsp;2003 (<a href="ftp://ftp.isi.edu/in-notes/rfc3319.txt">TXT</a>).</td></tr>
        !           780: <tr><td class="author-text" valign="top"><a name="RFC3396">[RFC3396]</a></td>
        !           781: <td class="author-text">Lemon, T. and S. Cheshire, &ldquo;<a href="http://tools.ietf.org/html/rfc3396">Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)</a>,&rdquo; RFC&nbsp;3396, November&nbsp;2002 (<a href="ftp://ftp.isi.edu/in-notes/rfc3396.txt">TXT</a>).</td></tr>
        !           782: <tr><td class="author-text" valign="top"><a name="RFC3397">[RFC3397]</a></td>
        !           783: <td class="author-text">Aboba, B. and S. Cheshire, &ldquo;<a href="http://tools.ietf.org/html/rfc3397">Dynamic Host Configuration Protocol (DHCP) Domain Search Option</a>,&rdquo; RFC&nbsp;3397, November&nbsp;2002 (<a href="ftp://ftp.isi.edu/in-notes/rfc3397.txt">TXT</a>).</td></tr>
        !           784: <tr><td class="author-text" valign="top"><a name="RFC3527">[RFC3527]</a></td>
        !           785: <td class="author-text">Kinnear, K., Stapp, M., Johnson, R., and J. Kumarasamy, &ldquo;<a href="http://tools.ietf.org/html/rfc3527">Link Selection sub-option for the Relay Agent Information Option for DHCPv4</a>,&rdquo; RFC&nbsp;3527, April&nbsp;2003 (<a href="ftp://ftp.isi.edu/in-notes/rfc3527.txt">TXT</a>).</td></tr>
        !           786: <tr><td class="author-text" valign="top"><a name="RFC3633">[RFC3633]</a></td>
        !           787: <td class="author-text">Troan, O. and R. Droms, &ldquo;<a href="http://tools.ietf.org/html/rfc3633">IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6</a>,&rdquo; RFC&nbsp;3633, December&nbsp;2003 (<a href="ftp://ftp.isi.edu/in-notes/rfc3633.txt">TXT</a>).</td></tr>
        !           788: <tr><td class="author-text" valign="top"><a name="RFC3646">[RFC3646]</a></td>
        !           789: <td class="author-text">Droms, R., &ldquo;<a href="http://tools.ietf.org/html/rfc3646">DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)</a>,&rdquo; RFC&nbsp;3646, December&nbsp;2003 (<a href="ftp://ftp.isi.edu/in-notes/rfc3646.txt">TXT</a>).</td></tr>
        !           790: <tr><td class="author-text" valign="top"><a name="RFC3679">[RFC3679]</a></td>
        !           791: <td class="author-text">Droms, R., &ldquo;<a href="http://tools.ietf.org/html/rfc3679">Unused Dynamic Host Configuration Protocol (DHCP) Option Codes</a>,&rdquo; RFC&nbsp;3679, January&nbsp;2004 (<a href="ftp://ftp.isi.edu/in-notes/rfc3679.txt">TXT</a>).</td></tr>
        !           792: <tr><td class="author-text" valign="top"><a name="RFC3898">[RFC3898]</a></td>
        !           793: <td class="author-text">Kalusivalingam, V., &ldquo;<a href="http://tools.ietf.org/html/rfc3898">Network Information Service (NIS) Configuration Options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)</a>,&rdquo; RFC&nbsp;3898, October&nbsp;2004 (<a href="ftp://ftp.isi.edu/in-notes/rfc3898.txt">TXT</a>).</td></tr>
        !           794: <tr><td class="author-text" valign="top"><a name="RFC3925">[RFC3925]</a></td>
        !           795: <td class="author-text">Littlefield, J., &ldquo;<a href="http://tools.ietf.org/html/rfc3925">Vendor-Identifying Vendor Options for Dynamic Host Configuration Protocol version 4 (DHCPv4)</a>,&rdquo; RFC&nbsp;3925, October&nbsp;2004 (<a href="ftp://ftp.isi.edu/in-notes/rfc3925.txt">TXT</a>).</td></tr>
        !           796: <tr><td class="author-text" valign="top"><a name="RFC3942">[RFC3942]</a></td>
        !           797: <td class="author-text">Volz, B., &ldquo;<a href="http://tools.ietf.org/html/rfc3942">Reclassifying Dynamic Host Configuration Protocol version 4 (DHCPv4) Options</a>,&rdquo; RFC&nbsp;3942, November&nbsp;2004 (<a href="ftp://ftp.isi.edu/in-notes/rfc3942.txt">TXT</a>).</td></tr>
        !           798: <tr><td class="author-text" valign="top"><a name="RFC4075">[RFC4075]</a></td>
        !           799: <td class="author-text">Kalusivalingam, V., &ldquo;<a href="http://tools.ietf.org/html/rfc4075">Simple Network Time Protocol (SNTP) Configuration Option for DHCPv6</a>,&rdquo; RFC&nbsp;4075, May&nbsp;2005 (<a href="ftp://ftp.isi.edu/in-notes/rfc4075.txt">TXT</a>).</td></tr>
        !           800: <tr><td class="author-text" valign="top"><a name="RFC4242">[RFC4242]</a></td>
        !           801: <td class="author-text">Venaas, S., Chown, T., and B. Volz, &ldquo;<a href="http://tools.ietf.org/html/rfc4242">Information Refresh Time Option for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)</a>,&rdquo; RFC&nbsp;4242, November&nbsp;2005 (<a href="ftp://ftp.isi.edu/in-notes/rfc4242.txt">TXT</a>).</td></tr>
        !           802: <tr><td class="author-text" valign="top"><a name="RFC4280">[RFC4280]</a></td>
        !           803: <td class="author-text">Chowdhury, K., Yegani, P., and L. Madour, &ldquo;<a href="http://tools.ietf.org/html/rfc4280">Dynamic Host Configuration Protocol (DHCP) Options for Broadcast and Multicast Control Servers</a>,&rdquo; RFC&nbsp;4280, November&nbsp;2005 (<a href="ftp://ftp.isi.edu/in-notes/rfc4280.txt">TXT</a>).</td></tr>
        !           804: <tr><td class="author-text" valign="top"><a name="RFC4388">[RFC4388]</a></td>
        !           805: <td class="author-text">Woundy, R. and K. Kinnear, &ldquo;<a href="http://tools.ietf.org/html/rfc4388">Dynamic Host Configuration Protocol (DHCP) Leasequery</a>,&rdquo; RFC&nbsp;4388, February&nbsp;2006 (<a href="ftp://ftp.isi.edu/in-notes/rfc4388.txt">TXT</a>).</td></tr>
        !           806: <tr><td class="author-text" valign="top"><a name="RFC4580">[RFC4580]</a></td>
        !           807: <td class="author-text">Volz, B., &ldquo;<a href="http://tools.ietf.org/html/rfc4580">Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Relay Agent Subscriber-ID Option</a>,&rdquo; RFC&nbsp;4580, June&nbsp;2006 (<a href="ftp://ftp.isi.edu/in-notes/rfc4580.txt">TXT</a>).</td></tr>
        !           808: <tr><td class="author-text" valign="top"><a name="RFC4649">[RFC4649]</a></td>
        !           809: <td class="author-text">Volz, B., &ldquo;<a href="http://tools.ietf.org/html/rfc4649">Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Relay Agent Remote-ID Option</a>,&rdquo; RFC&nbsp;4649, August&nbsp;2006 (<a href="ftp://ftp.isi.edu/in-notes/rfc4649.txt">TXT</a>).</td></tr>
        !           810: <tr><td class="author-text" valign="top"><a name="RFC4701">[RFC4701]</a></td>
        !           811: <td class="author-text">Stapp, M., Lemon, T., and A. Gustafsson, &ldquo;<a href="http://tools.ietf.org/html/rfc4701">A DNS Resource Record (RR) for Encoding Dynamic Host Configuration Protocol (DHCP) Information (DHCID RR)</a>,&rdquo; RFC&nbsp;4701, October&nbsp;2006 (<a href="ftp://ftp.isi.edu/in-notes/rfc4701.txt">TXT</a>).</td></tr>
        !           812: <tr><td class="author-text" valign="top"><a name="RFC4702">[RFC4702]</a></td>
        !           813: <td class="author-text">Stapp, M., Volz, B., and Y. Rekhter, &ldquo;<a href="http://tools.ietf.org/html/rfc4702">The Dynamic Host Configuration Protocol (DHCP) Client Fully Qualified Domain Name (FQDN) Option</a>,&rdquo; RFC&nbsp;4702, October&nbsp;2006 (<a href="ftp://ftp.isi.edu/in-notes/rfc4702.txt">TXT</a>).</td></tr>
        !           814: <tr><td class="author-text" valign="top"><a name="RFC4703">[RFC4703]</a></td>
        !           815: <td class="author-text">Stapp, M. and B. Volz, &ldquo;<a href="http://tools.ietf.org/html/rfc4703">Resolution of Fully Qualified Domain Name (FQDN) Conflicts among Dynamic Host Configuration Protocol (DHCP) Clients</a>,&rdquo; RFC&nbsp;4703, October&nbsp;2006 (<a href="ftp://ftp.isi.edu/in-notes/rfc4703.txt">TXT</a>).</td></tr>
        !           816: <tr><td class="author-text" valign="top"><a name="RFC4704">[RFC4704]</a></td>
        !           817: <td class="author-text">Volz, B., &ldquo;<a href="http://tools.ietf.org/html/rfc4704">The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Client Fully Qualified Domain Name (FQDN) Option</a>,&rdquo; RFC&nbsp;4704, October&nbsp;2006 (<a href="ftp://ftp.isi.edu/in-notes/rfc4704.txt">TXT</a>).</td></tr>
        !           818: <tr><td class="author-text" valign="top"><a name="draft-failover">[draft-failover]</a></td>
        !           819: <td class="author-text">Droms, R., &ldquo;<a href="https://www.isc.org/sw/dhcp/drafts/draft-ietf-dhc-failover-12.txt">DHCP Failover Protocol</a>,&rdquo; March&nbsp;2003.</td></tr>
        !           820: </table>
        !           821: 
        !           822: <a name="rfc.authors"></a><br /><hr />
        !           823: <table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc">&nbsp;TOC&nbsp;</a></td></tr></table>
        !           824: <h3>Author's Address</h3>
        !           825: <table width="99%" border="0" cellpadding="0" cellspacing="0">
        !           826: <tr><td class="author-text">&nbsp;</td>
        !           827: <td class="author-text">David W. Hankins</td></tr>
        !           828: <tr><td class="author-text">&nbsp;</td>
        !           829: <td class="author-text">Internet Systems Consortium,
        !           830:                                 Inc.</td></tr>
        !           831: <tr><td class="author-text">&nbsp;</td>
        !           832: <td class="author-text">950 Charter Street</td></tr>
        !           833: <tr><td class="author-text">&nbsp;</td>
        !           834: <td class="author-text">Redwood City, CA  94063</td></tr>
        !           835: <tr><td class="author" align="right">Phone:&nbsp;</td>
        !           836: <td class="author-text">+1 650 423 1300</td></tr>
        !           837: <tr><td class="author" align="right">Email:&nbsp;</td>
        !           838: <td class="author-text"><a href="mailto:David_Hankins@isc.org">David_Hankins@isc.org</a></td></tr>
        !           839: </table>
        !           840: </body></html>

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