INTERNET-DRAFT Andreas Gustafsson
draft-ietf-dnsind-dhcp-rr-00.txt Internet Engines, Inc.
October 1999
A DNS RR for encoding DHCP information
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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Abstract
This document describes a DNS RR for use by DHCP servers that need to
store state information in the DNS.
Introduction
A set of procedures to allow DHCP servers [RFC2131] to automatically
update the DNS [RFC1034, RFC1035] is proposed in [DHCPDNS].
A situation can arise where multiple DHCP clients request the same
DNS name from their (possibly distinct) DHCP servers. To resolve
such conflicts, [DHCPDNS] proposes storing client identifiers in the
DNS to unambiguously associate domain names with the DHCP clients
"owning" them. Early versions of [DHCPDNS] proposed using TXT
records for encoding this information; the current version specifies
the use of KEY records.
In the interest of clarity, it would be preferable for this DHCP
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information to use a distinct RR type rather than the existing KEY
type. A separate RR type can also improve efficiency by avoiding the
unnecessary transmission of unrelated KEY records.
This memo defines a distinct RR type for use by DHCP servers, the
"DHCP" RR.
The DHCP RR
The DHCP RR is defined with mnemonic DHCP and type code <TBD>.
DHCP RDATA format
The RDATA section of a DHCP RR in transmission contains RDLENGTH
bytes of binary data. The format of this data and its interpretation
by DHCP servers and clients, including the interpretation of multiple
DHCP RRs at the same domain name, are TBD. [This part of the
specification should be driven by the needs of, and written in
cooperation with, the DHCP Working Group and the authors of
[DHCPDNS]].
DNS software should consider the RDATA section to be opaque. In DNS
master files, the RDATA is represented as a hexadecimal string with
an optional "0x" or "0X" prefix. Periods (".") may be inserted
anywhere after the "0x" for readability. This format is identical to
that of the NSAP RR [RFC1706]. The number of hexadecimal digits MUST
be even.
Example
A DHCP server allocating the IPv4 address 10.0.0.1 to a client
"client.org.nil" might associate eight bytes of housekeeping
information with the client as follows:
client.org.nil. A 10.0.0.1
Security Considerations
The DHCP record as such does not introduce any new security problems
into the DNS. However, care should be taken not to store sensitive
information in DHCP records, since they are published along with
other DNS data. Note that even the hardware addresses of DHCP
clients may be considered sensitive information.
IANA Considerations
The IANA is requested to allocate an RR type number for the DHCP
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record type from the regular RR type number range.
References
[RFC1035] - Domain Names - Implementation and Specifications, P.
Mockapetris, November 1987.
[RFC1034] - Domain Names - Concepts and Facilities, P. Mockapetris,
November 1987.
[RFC1706] - DNS NSAP Resource Records, B. Manning, R. Colella,
October 1994.
[RFC2131] - Dynamic Host Configuration Protocol, R. Droms, March
1997.
[DHCPDNS] - draft-ietf-dhc-dhcp-dns-*.txt
Author's Address
Andreas Gustafsson
Internet Engines, Inc.
950 Charter Street
Redwood City, CA 94063
USA
Phone: +1 650 779 6004
Email: gson@iengines.net
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