Resolution of Fully Qualified Domain Name (FQDN) Conflicts among Dynamic Host Configuration Protocol (DHCP) Clients
RFC 4703

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Network Working Group                                           M. Stapp
Request for Comments: 4703                                       B. Volz
Category: Standards Track                            Cisco Systems, Inc.
                                                            October 2006

       Resolution of Fully Qualified Domain Name (FQDN) Conflicts
        among Dynamic Host Configuration Protocol (DHCP) Clients

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

   The Dynamic Host Configuration Protocol (DHCP) provides a mechanism
   for host configuration that includes dynamic assignment of IP
   addresses and fully qualified domain names.  To maintain accurate
   name-to-IP-address and IP-address-to-name mappings in the DNS, these
   dynamically assigned addresses and fully qualified domain names
   (FQDNs) require updates to the DNS.  This document identifies
   situations in which conflicts in the use of fully qualified domain
   names may arise among DHCP clients and servers, and it describes a
   strategy for the use of the DHCID DNS resource record (RR) in
   resolving those conflicts.

Stapp & Volz                Standards Track                     [Page 1]
RFC 4703              Resolution of FQDN Conflicts          October 2006

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. Issues with DNS Update in DHCP Environments .....................4
      3.1. Client Misconfiguration ....................................4
      3.2. Multiple DHCP Servers ......................................5
   4. Use of the DHCID RR .............................................5
   5. Procedures for Performing DNS Updates ...........................6
      5.1. Error Return Codes .........................................6
      5.2. Dual IPv4/IPv6 Client Considerations .......................6
      5.3. Adding A and/or AAAA RRs to DNS ............................7
           5.3.1. Initial DHCID RR Request ............................7
           5.3.2. DNS UPDATE When FQDN in Use .........................7
           5.3.3. FQDN in Use by Another Client .......................8
      5.4. Adding PTR RR Entries to DNS ...............................8
      5.5. Removing Entries from DNS ..................................9
      5.6. Updating Other RRs ........................................10
   6. Security Considerations ........................................10
   7. Acknowledgements ...............................................11
   8. References .....................................................11
      8.1. Normative References ......................................11
      8.2. Informative References ....................................11

Stapp & Volz                Standards Track                     [Page 2]
RFC 4703              Resolution of FQDN Conflicts          October 2006

1.  Introduction

   "The Client FQDN Option" [8] includes a description of the operation
   of [4] clients and servers that use the DHCPv4 client FQDN option.
   "The DHCPv6 Client FQDN Option" [9] includes a description of the
   operation of [5] clients and servers that use the DHCPv6 client FQDN
   option.  Through the use of the client FQDN option, DHCP clients and
   servers can negotiate the client's FQDN and the allocation of
   responsibility for updating the DHCP client's A and/or AAAA RRs.
   This document identifies situations in which conflicts in the use of
   FQDNs may arise among DHCP clients and servers, and it describes a
   strategy for the use of the DHCID DNS resource record [2] in
   resolving those conflicts.

   In any case, whether a site permits all, some, or no DHCP servers and
   clients to perform DNS updates ([3], [10]) into the zones that it
   controls is entirely a matter of local administrative policy.  This
   document does not require any specific administrative policy, and
   does not propose one.  The range of possible policies is very broad,
   from sites where only the DHCP servers have been given credentials
   that the DNS servers will accept, to sites where each individual DHCP
   client has been configured with credentials that allow the client to
   modify its own FQDN.  Compliant implementations MAY support some or
   all of these possibilities.  Furthermore, this specification applies
   only to DHCP client and server processes; it does not apply to other
   processes that initiate DNS updates.

2.  Terminology