Network Working Group M. Stapp
Request for Comments: 4701 Cisco Systems, Inc.
Category: Standards Track T. Lemon
Nominum, Inc.
A. Gustafsson
Araneus Information Systems Oy
October 2006
A DNS Resource Record (RR) for Encoding
Dynamic Host Configuration Protocol (DHCP) Information (DHCID RR)
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
It is possible for Dynamic Host Configuration Protocol (DHCP) clients
to attempt to update the same DNS Fully Qualified Domain Name (FQDN)
or to update a DNS FQDN that has been added to the DNS for another
purpose as they obtain DHCP leases. Whether the DHCP server or the
clients themselves perform the DNS updates, conflicts can arise. To
resolve such conflicts, RFC 4703 proposes storing client identifiers
in the DNS to unambiguously associate domain names with the DHCP
clients to which they refer. This memo defines a distinct Resource
Record (RR) type for this purpose for use by DHCP clients and
servers: the "DHCID" RR.
Stapp, et al. Standards Track [Page 1]
RFC 4701 The DHCID RR October 2006
Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................3
3. The DHCID RR ....................................................3
3.1. DHCID RDATA Format .........................................3
3.2. DHCID Presentation Format ..................................4
3.3. The DHCID RR Identifier Type Codes .........................4
3.4. The DHCID RR Digest Type Code ..............................4
3.5. Computation of the RDATA ...................................5
3.5.1. Using the Client's DUID .............................5
3.5.2. Using the Client Identifier Option ..................6
3.5.3. Using the Client's htype and chaddr .................6
3.6. Examples ...................................................6
3.6.1. Example 1 ...........................................6
3.6.2. Example 2 ...........................................7
3.6.3. Example 3 ...........................................7
4. Use of the DHCID RR .............................................8
5. Updater Behavior ................................................8
6. Security Considerations .........................................8
7. IANA Considerations .............................................9
8. Acknowledgements ................................................9
9. References ......................................................9
9.1. Normative References .......................................9
9.2. Informative References ....................................10
Stapp, et al. Standards Track [Page 2]
RFC 4701 The DHCID RR October 2006
1. Introduction
A set of procedures to allow DHCP [7] [11] clients and servers to
automatically update the DNS ([3], [4]) is proposed in [1].
Conflicts can arise if multiple DHCP clients wish to use the same DNS
name or a DHCP client attempts to use a name added for another
purpose. To resolve such conflicts, [1] proposes storing client
identifiers in the DNS to unambiguously associate domain names with
the DHCP clients using them. In the interest of clarity, it is
preferable for this DHCP information to use a distinct RR type. This
memo defines a distinct RR for this purpose for use by DHCP clients
or servers: the "DHCID" RR.
In order to obscure potentially sensitive client identifying
information, the data stored is the result of a one-way SHA-256 hash
computation. The hash includes information from the DHCP client's
message as well as the domain name itself, so that the data stored in
the DHCID RR will be dependent on both the client identification used
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