


ISC-DHCP-REFERENCES                                           D. Hankins
                                                                     ISC
                                                                May 2007


                     ISC DHCP References Collection

Copyright Notice

   Copyright (c) 2006-2007,2009 by Internet Systems Consortium, Inc.
   ("ISC")

   Permission to use, copy, modify, and distribute this software for any
   purpose with or without fee is hereby granted, provided that the
   above copyright notice and this permission notice appear in all
   copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY
   SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
   OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Abstract

   This document describes a collection of Reference material that ISC
   DHCP has been implemented to.






















Hankins                                                         [Page 1]

                     ISC DHCP References Collection             May 2007


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3

   2.  Definition: Reference Implementation . . . . . . . . . . . . .  3

   3.  Low Layer References . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Ethernet Protocol References . . . . . . . . . . . . . . .  6
     3.2.  Token Ring Protocol References . . . . . . . . . . . . . .  6
     3.3.  FDDI Protocol References . . . . . . . . . . . . . . . . .  6
     3.4.  Internet Protocol Version 4 References . . . . . . . . . .  6
     3.5.  Unicast Datagram Protocol References . . . . . . . . . . .  6

   4.  BOOTP Protocol References  . . . . . . . . . . . . . . . . . .  6

   5.  DHCP Protocol References . . . . . . . . . . . . . . . . . . .  7
     5.1.  DHCPv4 Protocol  . . . . . . . . . . . . . . . . . . . . .  7
       5.1.1.  Core Protocol References . . . . . . . . . . . . . . .  7
     5.2.  DHCPv6 Protocol References . . . . . . . . . . . . . . . .  7
     5.3.  DHCP Option References . . . . . . . . . . . . . . . . . .  8
       5.3.1.  Relay Agent Information Option Options . . . . . . . . 10
       5.3.2.  Dynamic DNS Updates References . . . . . . . . . . . . 10
       5.3.3.  Experimental: Failover References  . . . . . . . . . . 11
     5.4.  DHCP Procedures  . . . . . . . . . . . . . . . . . . . . . 11

   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11

   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15























Hankins                                                         [Page 2]

                     ISC DHCP References Collection             May 2007


1.  Introduction

   As a little historical anecdote, ISC DHCP once packaged all the
   relevant RFCs and standards documents along with the software
   package.  Until one day when a voice was heard from one of the many
   fine institutions that build and distribute this software... they
   took issue with the IETF's copyright on the RFC's.  It seems the
   IETF's copyrights don't allow modification of RFC's (except for
   translation purposes).

   Our main purpose in providing the RFCs is to aid in documentation,
   but since RFCs are now available widely from many points of
   distribution on the Internet, there is no real need to provide the
   documents themselves.  So, this document has been created in their
   stead, to list the various IETF RFCs one might want to read, and to
   comment on how well (or poorly) we have managed to implement them.


2.  Definition: Reference Implementation

   ISC DHCP, much like its other cousins in ISC software, is self-
   described as a 'Reference Implementation.'  There has been a great
   deal of confusion about this term.  Some people seem to think that
   this term applies to any software that once passed a piece of
   reference material on its way to market (but may do quite a lot of
   things that aren't described in any reference, or may choose to
   ignore the reference it saw entirely).  Other folks get confused by
   the word 'reference' and understand that to mean that there is some
   special status applied to the software - that the software itself is
   the reference by which all other software is measured.  Something
   along the lines of being "The DHCP Protocol's Reference Clock," it is
   supposed.

   The truth is actually quite a lot simpler.  Reference implementations
   are software packages which were written to behave precisely as
   appears in reference material.  They are written "to match
   reference."

   If the software has a behaviour that manifests itself externally
   (whether it be something as simple as the 'wire format' or something
   higher level, such as a complicated behaviour that arises from
   multiple message exchanges), that behaviour must be found in a
   reference document.

   Anything else is a bug, the only question is whether the bug is in
   reference or software (failing to implement the reference).

   This means:



Hankins                                                         [Page 3]

                     ISC DHCP References Collection             May 2007


   o  To produce new externally-visible behaviour, one must first
      provide a reference.

   o  Before changing externally visible behaviour to work around simple
      incompatibilities in any other implementation, one must first
      provide a reference.

   That is the lofty goal, at any rate.  It's well understood that,
   especially because the ISC DHCP Software package has not always been
   held to this standard (but not entirely due to it), there are many
   non-referenced behaviours within ISC DHCP.

   The primary goal of reference implementation is to prove the
   reference material.  If the reference material is good, then you
   should be able to sit down and write a program that implements the
   reference, to the word, and come to an implementation that is
   distinguishable from others in the details, but not in the facts of
   operating the protocol.  This means that there is no need for
   'special knowledge' to work around arcane problems that were left
   undocumented.  No secret handshakes need to be learned to be imparted
   with the necessary "real documentation".

   Also, by accepting only reference as the guidebook for ISC DHCP's
   software implementation, anyone who can make an impact on the color
   texture or form of that reference has a (somewhat indirect) voice in
   ISC DHCP's software design.  As the IETF RFC's have been selected as
   the source of reference, that means everyone on the Internet with the
   will to participate has a say.


3.  Low Layer References

   It may surprise you to realize that ISC DHCP implements 802.1
   'Ethernet' framing, Token Ring, and FDDI.  In order to bridge the gap
   there between these physical and DHCP layers, it must also implement
   IP and UDP framing.

   The reason for this stems from Unix systems' handling of BSD sockets
   (the general way one might engage in transmission of UDP packets) on
   unconfigured interfaces, or even the handling of broadcast addressing
   on configured interfaces.

   There are a few things that DHCP servers, relays, and clients all
   need to do in order to speak the DHCP protocol in strict compliance
   with RFC2131 [RFC2131].

   1.  Transmit a UDP packet from IP:0.0.0.0 Ethernet:Self, destined to
       IP:255.255.255.255 LinkLayer:Broadcast on an unconfigured (no IP



Hankins                                                         [Page 4]

                     ISC DHCP References Collection             May 2007


       address yet) interface.

   2.  Receive a UDP packet from IP:remote-system LinkLayer:remote-
       system, destined to IP:255.255.255.255 LinkLayer:Broadcast, again
       on an unconfigured interface.

   3.  Transmit a UDP packet from IP:Self, Ethernet:Seelf, destined to
       IP:remote-system LinkLayer:remote-system, without transmitting a
       single ARP.

   4.  And of course the simple case, a regular IP unicast that is
       routed via the usual means (so it may be direct to a local
       system, with ARP providing the glue, or it may be to a remote
       system via one or more routers as normal).  In this case, the
       interfaces are always configured.

   The above isn't as simple as it sounds on a regular BSD socket.  Many
   unix implementations will transmit broadcasts not to 255.255.255.255,
   but to x.y.z.255 (where x.y.z is the system's local subnet).  Such
   packets are not received by several known DHCP client implementations
   - and it's not their fault, RFC2131 [RFC2131] very explicitly demands
   that these packets' IP destination addresses be set to
   255.255.255.255.

   Receiving packets sent to 255.255.255.255 isn't a problem on most
   modern unixes...so long as the interface is configured.  When there
   is no IPv4 address on the interface, things become much more murky.

   So, for this convoluted and unfortunate state of affairs in the unix
   systems of the day ISC DHCP was manufactured, in order to do what it
   needs not only to implement the reference but to interoperate with
   other implementations, the software must create some form of raw
   socket to operate on.

   What it actually does is create, for each interface detected on the
   system, a Berkeley Packet Filter socket (or equivalent), and program
   it with a filter that brings in only DHCP packets.  A "fallback" UDP
   Berkeley socket is generally also created, a single one no matter how
   many interfaces.  Should the software need to transmit a contrived
   packet to the local network the packet is formed piece by piece and
   transmitted via the BPF socket.  Hence the need to implement many
   forms of Link Layer framing and above.  The software gets away with
   not having to implement IP routing tables as well by simply utilizing
   the aforementioned 'fallback' UDP socket when unicasting between two
   configured systems is the need.

   Modern unixes have opened up some facilities that diminish how much
   of this sort of nefarious kludgery is necessary, but have not found



Hankins                                                         [Page 5]

                     ISC DHCP References Collection             May 2007


   the state of affairs absolutely absolved.  In particular, one might
   now unicast without ARP by inserting an entry into the ARP cache
   prior to transmitting.  Unconfigured interfaces remain the sticking
   point, however...on virtually no modern unixes is it possible to
   receive broadcast packets unless a local IPv4 address has been
   configured, unless it is done with raw sockets.

3.1.  Ethernet Protocol References

   ISC DHCP Implements Ethernet Version 2 ("DIX"), which is a variant of
   IEEE 802.2.  No good reference of this framing is known to exist at
   this time, but it is vaguely described in RFC894 [RFC0894] (see the
   section titled "Packet format"), and the following URL is also
   thought to be useful.

   http://en.wikipedia.org/wiki/DIX

3.2.  Token Ring Protocol References

   IEEE 802.5 defines the Token Ring framing format used by ISC DHCP.

3.3.  FDDI Protocol References

   RFC1188 [RFC1188] is the most helpful reference ISC DHCP has used to
   form FDDI packets.

3.4.  Internet Protocol Version 4 References

   RFC760 [RFC0760] fundamentally defines the bare IPv4 protocol which
   ISC DHCP implements.

3.5.  Unicast Datagram Protocol References

   RFC768 [RFC0768] defines the User Datagram Protocol that ultimately
   carries the DHCP or BOOTP protocol.  The destination DHCP server port
   is 67, the client port is 68.  Source ports are irrelevant.


4.  BOOTP Protocol References

   The DHCP Protocol is strange among protocols in that it is grafted
   over the top of another protocol - BOOTP (but we don't call it "DHCP
   over BOOTP" like we do, say "TCP over IP").  BOOTP and DHCP share UDP
   packet formats - DHCP is merely a conventional use of both BOOTP
   header fields and the trailing 'options' space.

   The ISC DHCP server supports BOOTP clients conforming to RFC951
   [RFC0951] and RFC1542 [RFC1542].



Hankins                                                         [Page 6]

                     ISC DHCP References Collection             May 2007


5.  DHCP Protocol References

5.1.  DHCPv4 Protocol

   "The DHCP[v4] Protocol" is not defined in a single document.  The
   following collection of references of what ISC DHCP terms "The DHCPv4
   Protocol".

5.1.1.  Core Protocol References

   RFC2131 [RFC2131] defines the protocol format and procedures.  ISC
   DHCP is not known to diverge from this document in any way.  There
   are, however, a few points on which different implementations have
   arisen out of vagueries in the document.  DHCP Clients exist which,
   at one time, present themselves as using a Client Identifier Option
   which is equal to the client's hardware address.  Later, the client
   transmits DHCP packets with no Client Identifier Option present -
   essentially identifying themselves using the hardware address.  Some
   DHCP Servers have been developed which identify this client as a
   single client.  ISC has interpreted RFC2131 to indicate that these
   clients must be treated as two separate entities (and hence two,
   separate addresses).  Client behaviour (Embedded Windows products)
   has developed that relies on the former implementation, and hence is
   incompatible with the latter.  Also, RFC2131 demands explicitly that
   some header fields be zeroed upon certain message types.  The ISC
   DHCP Server instead copies many of these fields from the packet
   received from the client or relay, which may not be zero.  It is not
   known if there is a good reason for this that has not been
   documented.

   RFC2132 [RFC2132] defines the initial set of DHCP Options and
   provides a great deal of guidance on how to go about formatting and
   processing options.  The document unfortunately waffles to a great
   extent about the NULL termination of DHCP Options, and some DHCP
   Clients (Windows 95) have been implemented that rely upon DHCP
   Options containing text strings to be NULL-terminated (or else they
   crash).  So, ISC DHCP detects if clients null-terminate the host-name
   option and, if so, null terminates any text options it transmits to
   the client.  It also removes NULL termination from any known text
   option it receives prior to any other processing.

5.2.  DHCPv6 Protocol References

   For now there is only one document that specifies the DHCPv6 protocol
   (there have been no updates yet), RFC3315 [RFC3315].

   Support for DHCPv6 was added first in version 4.0.0.  The server and
   client support only IA_NA.  While the server does support multiple



Hankins                                                         [Page 7]

                     ISC DHCP References Collection             May 2007


   IA_NAs within one packet from the client, our client only supports
   sending one.  There is no relay support.

   DHCPv6 introduces some new and uncomfortable ideas to the common
   software library.

   1.  Options of zero length are normal in DHCPv6.  Currently, all ISC
       DHCP software treats zero-length options as errors.

   2.  Options sometimes may appear multiple times.  The common library
       used to treat all appearance of multiple options as specified in
       RFC2131 - to be concatenated.  DHCPv6 options may sometimes
       appear multiple times (such as with IA_NA or IAADDR), but often
       must not.

   3.  The same option space appears in DHCPv6 packets multiple times.
       If the packet was got via a relay, then the client's packet is
       stored to an option within the relay's packet...if there were two
       relays, this recurses.  At each of these steps, the root "DHCPv6
       option space" is used.  Further, a client packet may contain an
       IA_NA, which may contain an IAADDR - but really, in an abstract
       sense, this is again re-encapsulation of the DHCPv6 option space
       beneath options it also contains.

   Precisely how to correctly support the above conundrums has not quite
   yet been settled, so support is incomplete.

5.3.  DHCP Option References

   RFC2241 [RFC2241] defines options for Novell Directory Services.

   RFC2242 [RFC2242] defines an encapsulated option space for NWIP
   configuration.

   RFC2485 [RFC2485] defines the Open Group's UAP option.

   RFC2610 [RFC2610] defines options for the Service Location Protocol
   (SLP).

   RFC2937 [RFC2937] defines the Name Service Search Option (not to be
   confused with the domain-search option).  The Name Service Search
   Option allows eg nsswitch.conf to be reconfigured via dhcp.  The ISC
   DHCP server implements this option, and the ISC DHCP client is
   compatible...but does not by default install this option's value.
   One would need to make their relevant dhclient-script process this
   option in a way that is suitable for the system.

   RFC3004 [RFC3004] defines the User-Class option.  Note carefully that



Hankins                                                         [Page 8]

                     ISC DHCP References Collection             May 2007


   ISC DHCP currently does not implement to this reference, but has
   (inexplicably) selected an incompatible format: a plain text string.

   RFC3011 [RFC3011] defines the Subnet-Selection plain DHCPv4 option.
   Do not confuse this option with the relay agent "link selection" sub-
   option, although their behaviour is similar.

   RFC3319 [RFC3319] defines the SIP server options for DHCPv6.

   RFC3396 [RFC3396] documents both how long options may be encoded in
   DHCPv4 packets, and also how multiple instances of the same option
   code within a DHCPv4 packet will be decoded by receivers.

   RFC3397 [RFC3397] documents the Domain-Search Option, which allows
   the configuration of the /etc/resolv.conf 'search' parameter in a way
   that is RFC1035 [RFC1035] wire format compatible (in fact, it uses
   the RFC1035 wire format).  ISC DHCP has both client and server
   support, and supports RFC1035 name compression.

   RFC3646 [RFC3646] documents the DHCPv6 name-servers and domain-search
   options.

   RFC3633 [RFC3633] documents the Identity Association Prefix
   Delegation, which is included here for protocol wire reference, but
   which is not supported by ISC DHCP.

   RFC3679 [RFC3679] documents a number of options that were documented
   earlier in history, but were not made use of.

   RFC3898 [RFC3898] documents four NIS options for delivering NIS
   servers and domain information in DHCPv6.

   RFC3925 [RFC3925] documents a pair of Enterprise-ID delimited option
   spaces for vendors to use in order to inform servers of their "vendor
   class" (sort of like 'uname' or 'who and what am I'), and a means to
   deliver vendor-specific and vendor-documented option codes and
   values.

   RFC3942 [RFC3942] redefined the 'site local' option space.

   RFC4075 [RFC4075] defines the DHCPv6 SNTP Servers option.

   RFC4242 [RFC4242] defines the Information Refresh Time option, which
   advises DHCPv6 Information-Request clients to return for updated
   information.

   RFC4280 [RFC4280] defines two BCMS server options.




Hankins                                                         [Page 9]

                     ISC DHCP References Collection             May 2007


   RFC4388 [RFC4388] defined the DHCPv4 LEASEQUERY message type and a
   number of suitable response messages, for the purpose of sharing
   information about DHCP served addresses and clients.

   RFC4580 [RFC4580] defines a DHCPv6 subscriber-id option, which is
   similar in principle to the DHCPv4 relay agent option of the same
   name.

   RFC4649 [RFC4649] defines a DHCPv6 remote-id option, which is similar
   in principle to the DHCPv4 relay agent remote-id.

5.3.1.  Relay Agent Information Option Options

   RFC3046 [RFC3046] defines the Relay Agent Information Option and
   provides a number of sub-option definitions.

   RFC3256 [RFC3256] defines the DOCSIS Device Class sub-option.

   RFC3527 [RFC3527] defines the Link Selection sub-option.

5.3.2.  Dynamic DNS Updates References

   The collection of documents that describe the standards-based method
   to update dns names of DHCP clients starts most easily with RFC4703
   [RFC4703] to define the overall architecture, travels through RFCs
   4702 [RFC4702] and 4704 [RFC4704] to describe the DHCPv4 and DHCPv6
   FQDN options (to carry the client name), and ends up at RFC4701
   [RFC4701] which describes the DHCID RR used in DNS to perform a kind
   of atomic locking.

   ISC DHCP adoped early versions of these documents, and has not yet
   synched up with the final standards versions.

   For RFCs 4702 and 4704, the 'N' bit is not yet supported.  The result
   is that it is always set zero, and is ignored if set.

   For RFC4701, which is used to match client identities with names in
   the DNS as part of name conflict resolution.  Note that ISC DHCP's
   implementation of DHCIDs vary wildly from this specification.  First,
   ISC DHCP uses a TXT record in which the contents are stored in
   hexadecimal.  Second, there is a flaw in the selection of the
   'Identifier Type', which results in a completely different value
   being selected than was defined in an older revision of this
   document...also this field is one byte prior to hexadecimal encoding
   rather than two.  Third, ISC DHCP does not use a digest type code.
   Rather, all values for such TXT records are reached via an MD5 sum.
   In short, nothing is compatible, but the principle of the TXT record
   is the same as the standard DHCID record.  However, for DHCPv6 FQDN,



Hankins                                                        [Page 10]

                     ISC DHCP References Collection             May 2007


   we do use DHCID type code '2', as no other value really makes sense
   in our context.

5.3.3.  Experimental: Failover References

   The Failover Protocol defines a means by which two DHCP Servers can
   share all the relevant information about leases granted to DHCP
   clients on given networks, so that one of the two servers may fail
   and be survived by a server that can act responsibly.

   Unfortunately it has been quite some years since the last time this
   document was edited, and the authors no longer show any interest in
   fielding comments or improving the document.

   The status of this protocol is very unsure, but ISC's implementation
   of it has proven stable and suitable for use in sizable production
   environments.

   draft-ietf-dhc-failover-12.txt [draft-failover] describes the
   Failover Protocol.  In addition to what is described in this
   document, ISC DHCP has elected to make some experimental changes that
   may be revoked in a future version of ISC DHCP (if the draft authors
   do not adopt the new behaviour).  Specifically, ISC DHCP's POOLREQ
   behaviour differs substantially from what is documented in the draft,
   and the server also implements a form of 'MAC Address Affinity' which
   is not described in the failover document.  The full nature of these
   changes have been described on the IETF DHC WG mailing list (which
   has archives), and also in ISC DHCP's manual pages.  Also note that
   although this document references a RECOVER-WAIT state, it does not
   document a protocol number assignment for this state.  As a
   consequence, ISC DHCP has elected to use the value 254.

   RFC3074 [RFC3074] describes the Load Balancing Algorithm (LBA) that
   ISC DHCP uses in concert with the Failover protocol.  Note that
   versions 3.0.* are known to misimplement the hash algorithm (it will
   only use the low 4 bits of every byte of the hash bucket array).

5.4.  DHCP Procedures

   RFC2939 [RFC2939] explains how to go about obtaining a new DHCP
   Option code assignment.


6.  References

   [RFC0760]  Postel, J., "DoD standard Internet Protocol", RFC 760,
              January 1980.




Hankins                                                        [Page 11]

                     ISC DHCP References Collection             May 2007


   [RFC0768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              August 1980.

   [RFC0894]  Hornig, C., "Standard for the transmission of IP datagrams
              over Ethernet networks", STD 41, RFC 894, April 1984.

   [RFC0951]  Croft, B. and J. Gilmore, "Bootstrap Protocol", RFC 951,
              September 1985.

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

   [RFC1188]  Katz, D., "Proposed Standard for the Transmission of IP
              Datagrams over FDDI Networks", RFC 1188, October 1990.

   [RFC1542]  Wimer, W., "Clarifications and Extensions for the
              Bootstrap Protocol", RFC 1542, October 1993.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, March 1997.

   [RFC2132]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
              Extensions", RFC 2132, March 1997.

   [RFC2241]  Provan, D., "DHCP Options for Novell Directory Services",
              RFC 2241, November 1997.

   [RFC2242]  Droms, R. and K. Fong, "NetWare/IP Domain Name and
              Information", RFC 2242, November 1997.

   [RFC2485]  Drach, S., "DHCP Option for The Open Group's User
              Authentication Protocol", RFC 2485, January 1999.

   [RFC2610]  Perkins, C. and E. Guttman, "DHCP Options for Service
              Location Protocol", RFC 2610, June 1999.

   [RFC2937]  Smith, C., "The Name Service Search Option for DHCP",
              RFC 2937, September 2000.

   [RFC2939]  Droms, R., "Procedures and IANA Guidelines for Definition
              of New DHCP Options and Message Types", BCP 43, RFC 2939,
              September 2000.

   [RFC3004]  Stump, G., Droms, R., Gu, Y., Vyaghrapuri, R., Demirtjis,
              A., Beser, B., and J. Privat, "The User Class Option for
              DHCP", RFC 3004, November 2000.

   [RFC3011]  Waters, G., "The IPv4 Subnet Selection Option for DHCP",



Hankins                                                        [Page 12]

                     ISC DHCP References Collection             May 2007


              RFC 3011, November 2000.

   [RFC3046]  Patrick, M., "DHCP Relay Agent Information Option",
              RFC 3046, January 2001.

   [RFC3074]  Volz, B., Gonczi, S., Lemon, T., and R. Stevens, "DHC Load
              Balancing Algorithm", RFC 3074, February 2001.

   [RFC3256]  Jones, D. and R. Woundy, "The DOCSIS (Data-Over-Cable
              Service Interface Specifications) Device Class DHCP
              (Dynamic Host Configuration Protocol) Relay Agent
              Information Sub-option", RFC 3256, April 2002.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3319]  Schulzrinne, H. and B. Volz, "Dynamic Host Configuration
              Protocol (DHCPv6) Options for Session Initiation Protocol
              (SIP) Servers", RFC 3319, July 2003.

   [RFC3396]  Lemon, T. and S. Cheshire, "Encoding Long Options in the
              Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
              November 2002.

   [RFC3397]  Aboba, B. and S. Cheshire, "Dynamic Host Configuration
              Protocol (DHCP) Domain Search Option", RFC 3397,
              November 2002.

   [RFC3527]  Kinnear, K., Stapp, M., Johnson, R., and J. Kumarasamy,
              "Link Selection sub-option for the Relay Agent Information
              Option for DHCPv4", RFC 3527, April 2003.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

   [RFC3646]  Droms, R., "DNS Configuration options for Dynamic Host
              Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
              December 2003.

   [RFC3679]  Droms, R., "Unused Dynamic Host Configuration Protocol
              (DHCP) Option Codes", RFC 3679, January 2004.

   [RFC3898]  Kalusivalingam, V., "Network Information Service (NIS)
              Configuration Options for Dynamic Host Configuration
              Protocol for IPv6 (DHCPv6)", RFC 3898, October 2004.




Hankins                                                        [Page 13]

                     ISC DHCP References Collection             May 2007


   [RFC3925]  Littlefield, J., "Vendor-Identifying Vendor Options for
              Dynamic Host Configuration Protocol version 4 (DHCPv4)",
              RFC 3925, October 2004.

   [RFC3942]  Volz, B., "Reclassifying Dynamic Host Configuration
              Protocol version 4 (DHCPv4) Options", RFC 3942,
              November 2004.

   [RFC4075]  Kalusivalingam, V., "Simple Network Time Protocol (SNTP)
              Configuration Option for DHCPv6", RFC 4075, May 2005.

   [RFC4242]  Venaas, S., Chown, T., and B. Volz, "Information Refresh
              Time Option for Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 4242, November 2005.

   [RFC4280]  Chowdhury, K., Yegani, P., and L. Madour, "Dynamic Host
              Configuration Protocol (DHCP) Options for Broadcast and
              Multicast Control Servers", RFC 4280, November 2005.

   [RFC4388]  Woundy, R. and K. Kinnear, "Dynamic Host Configuration
              Protocol (DHCP) Leasequery", RFC 4388, February 2006.

   [RFC4580]  Volz, B., "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6) Relay Agent Subscriber-ID Option", RFC 4580,
              June 2006.

   [RFC4649]  Volz, B., "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6) Relay Agent Remote-ID Option", RFC 4649,
              August 2006.

   [RFC4701]  Stapp, M., Lemon, T., and A. Gustafsson, "A DNS Resource
              Record (RR) for Encoding Dynamic Host Configuration
              Protocol (DHCP) Information (DHCID RR)", RFC 4701,
              October 2006.

   [RFC4702]  Stapp, M., Volz, B., and Y. Rekhter, "The Dynamic Host
              Configuration Protocol (DHCP) Client Fully Qualified
              Domain Name (FQDN) Option", RFC 4702, October 2006.

   [RFC4703]  Stapp, M. and B. Volz, "Resolution of Fully Qualified
              Domain Name (FQDN) Conflicts among Dynamic Host
              Configuration Protocol (DHCP) Clients", RFC 4703,
              October 2006.

   [RFC4704]  Volz, B., "The Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6) Client Fully Qualified Domain Name (FQDN)
              Option", RFC 4704, October 2006.




Hankins                                                        [Page 14]

                     ISC DHCP References Collection             May 2007


   [draft-failover]
              Droms, R., "DHCP Failover Protocol", March 2003.


Author's Address

   David W. Hankins
   Internet Systems Consortium, Inc.
   950 Charter Street
   Redwood City, CA  94063

   Phone: +1 650 423 1300
   Email: David_Hankins@isc.org






































Hankins                                                        [Page 15]

