draft-ietf-dhc-fqdn-option-10.txt   draft-ietf-dhc-fqdn-option-11.txt 
DHC M. Stapp DHC M. Stapp
Internet-Draft B. Volz Internet-Draft B. Volz
Expires: August 19, 2005 Cisco Systems, Inc. Expires: March 28, 2006 Cisco Systems, Inc.
Y. Rekhter Y. Rekhter
Juniper Networks Juniper Networks
February 15, 2005 September 24, 2005
The DHCP Client FQDN Option The DHCP Client FQDN Option
<draft-ietf-dhc-fqdn-option-10.txt> <draft-ietf-dhc-fqdn-option-11.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions By submitting this Internet-Draft, each author represents that any
of Section 3 of RFC 3667. By submitting this Internet-Draft, each applicable patent or other IPR claims of which he or she is aware
author represents that any applicable patent or other IPR claims of have been or will be disclosed, and any of which he or she becomes
which he or she is aware have been or will be disclosed, and any of aware will be disclosed, in accordance with Section 6 of BCP 79.
which he or she become aware will be disclosed, in accordance with
RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as other groups may also distribute working documents as Internet-
Internet-Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 19, 2005. This Internet-Draft will expire on March 28, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document specifies a DHCP for IPv4, DHCPv4, option which can be This document specifies a DHCP for IPv4, DHCPv4, option which can be
used to exchange information about a DHCPv4 client's fully-qualified used to exchange information about a DHCPv4 client's fully-qualified
domain name and about responsibility for updating the DNS RR related domain name and about responsibility for updating the DNS RR related
to the client's address assignment. to the client's address assignment.
Table of Contents Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Models of Operation . . . . . . . . . . . . . . . . . . . 3 2.1. Models of Operation . . . . . . . . . . . . . . . . . . . 3
3. The Client FQDN Option . . . . . . . . . . . . . . . . . . . . 4 3. The Client FQDN Option . . . . . . . . . . . . . . . . . . . . 4
3.1 The Flags Field . . . . . . . . . . . . . . . . . . . . . 5 3.1. The Flags Field . . . . . . . . . . . . . . . . . . . . . 5
3.2 The RCODE Fields . . . . . . . . . . . . . . . . . . . . . 6 3.2. The RCODE Fields . . . . . . . . . . . . . . . . . . . . . 6
3.3 The Domain Name Field . . . . . . . . . . . . . . . . . . 6 3.3. The Domain Name Field . . . . . . . . . . . . . . . . . . 6
3.3.1 Deprecated ASCII Encoding . . . . . . . . . . . . . . 7 3.3.1. Deprecated ASCII Encoding . . . . . . . . . . . . . . 7
4. DHCP Client Behavior . . . . . . . . . . . . . . . . . . . . . 7 4. DHCP Client Behavior . . . . . . . . . . . . . . . . . . . . . 7
4.1 Interaction With Other Options . . . . . . . . . . . . . . 7 4.1. Interaction With Other Options . . . . . . . . . . . . . . 7
4.2 Client Desires to Update A RRs . . . . . . . . . . . . . . 8 4.2. Client Desires to Update A RRs . . . . . . . . . . . . . . 8
4.3 Client Desires Server to Do DNS Updates . . . . . . . . . 8 4.3. Client Desires Server to Do DNS Updates . . . . . . . . . 8
4.4 Client Desires No Server DNS Updates . . . . . . . . . . . 8 4.4. Client Desires No Server DNS Updates . . . . . . . . . . . 8
4.5 Domain Name and DNS Update Issues . . . . . . . . . . . . 9 4.5. Domain Name and DNS Update Issues . . . . . . . . . . . . 9
5. DHCP Server Behavior . . . . . . . . . . . . . . . . . . . . . 9 5. DHCP Server Behavior . . . . . . . . . . . . . . . . . . . . . 9
5.1 When to Perform DNS Updates . . . . . . . . . . . . . . . 10 5.1. When to Perform DNS Updates . . . . . . . . . . . . . . . 10
6. DNS Update Conflicts . . . . . . . . . . . . . . . . . . . . . 11 6. DNS Update Conflicts . . . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1 Normative References . . . . . . . . . . . . . . . . . . . 13 10.1. Normative References . . . . . . . . . . . . . . . . . . . 13
10.2 Informative References . . . . . . . . . . . . . . . . . . 13 10.2. Informative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . . . 16
1. Terminology 1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [1]. document are to be interpreted as described in RFC 2119 [1].
2. Introduction 2. Introduction
DNS ([2], [3]) maintains (among other things) the information about DNS ([2], [3]) maintains (among other things) the information about
skipping to change at page 3, line 29 skipping to change at page 3, line 29
The Dynamic Host Configuration Protocol for IPv4 (DHCPv4 or just DHCP The Dynamic Host Configuration Protocol for IPv4 (DHCPv4 or just DHCP
in this document) [5] provides a mechanism by which a host (a DHCP in this document) [5] provides a mechanism by which a host (a DHCP
client) can acquire certain configuration information, along with its client) can acquire certain configuration information, along with its
address. This document specifies a DHCP option, the Client FQDN address. This document specifies a DHCP option, the Client FQDN
option, which can be used by DHCP clients and servers to exchange option, which can be used by DHCP clients and servers to exchange
information about the client's fully-qualified domain name for an information about the client's fully-qualified domain name for an
address and who has the responsibility for updating the DNS with the address and who has the responsibility for updating the DNS with the
associated A and PTR RRs. associated A and PTR RRs.
2.1 Models of Operation 2.1. Models of Operation
When a DHCP client acquires a new address, a site's administrator may When a DHCP client acquires a new address, a site's administrator may
desire that one or both of the A RR for the client's FQDN and the PTR desire that one or both of the A RR for the client's FQDN and the PTR
RR for the acquired address be updated. Therefore, two separate DNS RR for the acquired address be updated. Therefore, two separate DNS
update transactions may occur. Acquiring an address via DHCP update transactions may occur. Acquiring an address via DHCP
involves two entities: a DHCP client and a DHCP server. In principle involves two entities: a DHCP client and a DHCP server. In principle
each of these entities could perform none, one, or both of the each of these entities could perform none, one, or both of the
transactions. However, in practice not all permutations make sense. transactions. However, in practice not all permutations make sense.
The DHCP Client FQDN option is primarily intended to operate in the The DHCP Client FQDN option is primarily intended to operate in the
following two cases: following two cases:
skipping to change at page 4, line 26 skipping to change at page 4, line 27
one. The range of possible policies is very broad, from sites where one. The range of possible policies is very broad, from sites where
only the DHCP servers have been given credentials that the DNS only the DHCP servers have been given credentials that the DNS
servers will accept, to sites where each individual DHCP client has servers will accept, to sites where each individual DHCP client has
been configured with credentials which allow the client to modify its been configured with credentials which allow the client to modify its
own domain name. Compliant implementations may support some or all own domain name. Compliant implementations may support some or all
of these possibilities. Furthermore, this specification applies only of these possibilities. Furthermore, this specification applies only
to DHCP client and server processes: it does not apply to other to DHCP client and server processes: it does not apply to other
processes which initiate DNS updates. processes which initiate DNS updates.
This document describes a new DHCP option which a client can use to This document describes a new DHCP option which a client can use to
convey all or part of its domain name to a DHCP server. convey all or part of its domain name to a DHCP server. Site-
Site-specific policy determines whether DHCP servers use the names specific policy determines whether DHCP servers use the names that
that clients offer or not, and what DHCP servers may do in cases clients offer or not, and what DHCP servers may do in cases where
where clients do not supply domain names. clients do not supply domain names.
3. The Client FQDN Option 3. The Client FQDN Option
To update the IP address to FQDN mapping a DHCP server needs to know To update the IP address to FQDN mapping a DHCP server needs to know
the FQDN of the client to which the server leases the address. To the FQDN of the client to which the server leases the address. To
allow the client to convey its FQDN to the server this document allow the client to convey its FQDN to the server this document
defines a new DHCP option, called "Client FQDN". The Client FQDN defines a new DHCP option, called "Client FQDN". The Client FQDN
option also contains Flags, which DHCP servers can use to convey option also contains Flags, which DHCP servers can use to convey
information about DNS updates to clients, and two deprecated RCODEs. information about DNS updates to clients, and two deprecated RCODEs.
skipping to change at page 5, line 14 skipping to change at page 5, line 14
The format of the Client FQDN option is: The format of the Client FQDN option is:
Code Len Flags RCODE1 RCODE2 Domain Name Code Len Flags RCODE1 RCODE2 Domain Name
+------+------+------+------+------+------+-- +------+------+------+------+------+------+--
| 81 | n | | | | ... | 81 | n | | | | ...
+------+------+------+------+------+------+-- +------+------+------+------+------+------+--
The above figure follows the conventions of [9]. The above figure follows the conventions of [9].
3.1 The Flags Field 3.1. The Flags Field
The format of the 1-octet Flags field is: The format of the 1-octet Flags field is:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| MBZ |N|E|O|S| | MBZ |N|E|O|S|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
The "S" bit indicates whether the server SHOULD or SHOULD NOT perform The "S" bit indicates whether the server SHOULD or SHOULD NOT perform
the A RR (FQDN to address) DNS updates. A client sets the bit to 0 the A RR (FQDN to address) DNS updates. A client sets the bit to 0
skipping to change at page 6, line 10 skipping to change at page 6, line 10
and MUST be supported by servers. 0 indicates a now deprecated ASCII and MUST be supported by servers. 0 indicates a now deprecated ASCII
encoding (see Section 3.3.1). A server MUST use the same encoding as encoding (see Section 3.3.1). A server MUST use the same encoding as
that used by the client. A server that does not support the that used by the client. A server that does not support the
deprecated ASCII encoding MUST ignore Client FQDN options that use deprecated ASCII encoding MUST ignore Client FQDN options that use
that encoding. that encoding.
The remaining bits in the Flags field are reserved for future The remaining bits in the Flags field are reserved for future
assignment. DHCP clients and servers which send the Client FQDN assignment. DHCP clients and servers which send the Client FQDN
option MUST clear the MBZ bits, and they MUST ignore these bits. option MUST clear the MBZ bits, and they MUST ignore these bits.
3.2 The RCODE Fields 3.2. The RCODE Fields
The RCODE1 and RCODE2 fields are deprecated. A client SHOULD set The RCODE1 and RCODE2 fields are deprecated. A client SHOULD set
these to 0 when sending the option and SHOULD ignore them on receipt. these to 0 when sending the option and SHOULD ignore them on receipt.
A server SHOULD set these to 255 when sending the option and MUST A server SHOULD set these to 255 when sending the option and MUST
ignore them on receipt. ignore them on receipt.
As this option with these fields is already in wide use, the fields As this option with these fields is already in wide use, the fields
are retained. These fields were originally defined for use by a DHCP are retained. These fields were originally defined for use by a DHCP
server to indicate to a DHCP client the Response Code from any A server to indicate to a DHCP client the Response Code from any A
(RCODE1) or PTR (RCODE2) RR DNS updates it has performed or a value (RCODE1) or PTR (RCODE2) RR DNS updates it has performed or a value
skipping to change at page 6, line 35 skipping to change at page 6, line 35
reason to deprecate them. reason to deprecate them.
If the client needs to confirm the DNS update has been done, it MAY If the client needs to confirm the DNS update has been done, it MAY
use a DNS query to check whether the mapping is up to date. However, use a DNS query to check whether the mapping is up to date. However,
depending on the load on the DHCP and DNS servers and the DNS depending on the load on the DHCP and DNS servers and the DNS
propagation delays, the client can only infer success. If the propagation delays, the client can only infer success. If the
information is not found to be up to date in DNS, the servers might information is not found to be up to date in DNS, the servers might
not have completed the updates or zone transfers, or not yet updated not have completed the updates or zone transfers, or not yet updated
their caches. their caches.
3.3 The Domain Name Field 3.3. The Domain Name Field
The Domain Name part of the option carries all or part of the FQDN of The Domain Name part of the option carries all or part of the FQDN of
a DHCP client. The data in the Domain Name field SHOULD appear in a DHCP client. The data in the Domain Name field SHOULD appear in
uncompressed DNS encoding as specified in RFC 1035 [3]. If the DHCP uncompressed DNS encoding as specified in RFC 1035 [3]. If the DHCP
client uses DNS encoding, it MUST set to 1 the the "E" bit in the client uses DNS encoding, it MUST set to 1 the the "E" bit in the
Flags field. In order to determine whether the FQDN has changed Flags field. In order to determine whether the FQDN has changed
between message exchanges, the client and server MUST NOT alter the between message exchanges, the client and server MUST NOT alter the
Domain Name field contents unless the FQDN has actually changed. Domain Name field contents unless the FQDN has actually changed.
A client MAY be configured with a fully-qualified domain name or with A client MAY be configured with a fully-qualified domain name or with
skipping to change at page 7, line 11 skipping to change at page 7, line 11
know the zone in which the name is to be embedded. know the zone in which the name is to be embedded.
To send a fully-qualified domain name, the Domain Name field is set To send a fully-qualified domain name, the Domain Name field is set
to the DNS encoded domain name including the terminating zero-length to the DNS encoded domain name including the terminating zero-length
label. To send a partial name, the Domain Name field is set to the label. To send a partial name, the Domain Name field is set to the
DNS encoded domain name without the terminating zero-length label. DNS encoded domain name without the terminating zero-length label.
A client MAY also leave the Domain Name field empty if it desires the A client MAY also leave the Domain Name field empty if it desires the
server to provide a name. server to provide a name.
3.3.1 Deprecated ASCII Encoding 3.3.1. Deprecated ASCII Encoding
A substantial population of clients implemented an earlier draft A substantial population of clients implemented an earlier draft
version of this specification, which permitted an ASCII encoding of version of this specification, which permitted an ASCII encoding of
the Domain Name field. Server implementations SHOULD be aware that the Domain Name field. Server implementations SHOULD be aware that
clients which send the Client FQDN option with the "E" bit set to 0 clients which send the Client FQDN option with the "E" bit set to 0
are using an ASCII encoding of the Domain Name field. Servers MAY be are using an ASCII encoding of the Domain Name field. Servers MAY be
prepared to return an ASCII encoded version of the Domain Name field prepared to return an ASCII encoded version of the Domain Name field
to such clients. Servers that are not prepared to return an ASCII to such clients. Servers that are not prepared to return an ASCII
encoded version MUST ignore the Client FQDN option if the "E" bit is encoded version MUST ignore the Client FQDN option if the "E" bit is
0. The use of ASCII encoding in this option SHOULD be considered 0. The use of ASCII encoding in this option SHOULD be considered
skipping to change at page 7, line 40 skipping to change at page 7, line 40
of RFC 1034 [2] and RFC 1035 [3]. However, implementers SHOULD also of RFC 1034 [2] and RFC 1035 [3]. However, implementers SHOULD also
be aware that some client software could be using UTF-8 [10] be aware that some client software could be using UTF-8 [10]
character encoding. This specification does not require any support character encoding. This specification does not require any support
for UTF-8. for UTF-8.
4. DHCP Client Behavior 4. DHCP Client Behavior
The following describes the behavior of a DHCP client that implements The following describes the behavior of a DHCP client that implements
the Client FQDN option. the Client FQDN option.
4.1 Interaction With Other Options 4.1. Interaction With Other Options
Other DHCP options MAY carry data that is related to the Domain Name Other DHCP options MAY carry data that is related to the Domain Name
field of the Client FQDN option. The Host Name option [9], for field of the Client FQDN option. The Host Name option [9], for
example, contains an ASCII string representation of the client's host example, contains an ASCII string representation of the client's host
name. In general, a client does not need to send redundant data, and name. In general, a client does not need to send redundant data, and
therefore clients which send the Client FQDN option in their messages therefore clients which send the Client FQDN option in their messages
MUST NOT also send the Host Name option. Clients which receive both MUST NOT also send the Host Name option. Clients which receive both
the Host Name option and the Client FQDN option from a server SHOULD the Host Name option and the Client FQDN option from a server SHOULD
prefer Client FQDN option data. Section 5 instructs servers to prefer Client FQDN option data. Section 5 instructs servers to
ignore the Host Name option in client messages which include the ignore the Host Name option in client messages which include the
Client FQDN option. Client FQDN option.
4.2 Client Desires to Update A RRs 4.2. Client Desires to Update A RRs
If a client that owns/maintains its own FQDN wants to be responsible If a client that owns/maintains its own FQDN wants to be responsible
for updating the FQDN to IP address mapping for the FQDN and for updating the FQDN to IP address mapping for the FQDN and
address(es) used by the client, the client MUST include the Client address(es) used by the client, the client MUST include the Client
FQDN option in the DHCPREQUEST message originated by the client. A FQDN option in the DHCPREQUEST message originated by the client. A
DHCP client MAY choose to include the Client FQDN option in its DHCP client MAY choose to include the Client FQDN option in its
DHCPDISCOVER messages as well as its DHCPREQUEST messages. The "S" DHCPDISCOVER messages as well as its DHCPREQUEST messages. The "S"
bit in the Flags field in the option MUST be 0. The "O" and "N" bits bit in the Flags field in the option MUST be 0. The "O" and "N" bits
MUST be 0. MUST be 0.
Once the client's DHCP configuration is completed (the client Once the client's DHCP configuration is completed (the client
receives a DHCPACK message and successfully completes a final check receives a DHCPACK message and successfully completes a final check
on the parameters passed in the message), the client MAY originate an on the parameters passed in the message), the client MAY originate an
update for the A RR (associated with the client's FQDN) unless the update for the A RR (associated with the client's FQDN) unless the
server has set the "S" bit to 1. If the "S" is 1, the DHCP client server has set the "S" bit to 1. If the "S" is 1, the DHCP client
SHOULD NOT initiate an update for the name in the server's returned SHOULD NOT initiate an update for the name in the server's returned
Client FQDN option Domain Name field. However, a DHCP client that is Client FQDN option Domain Name field. However, a DHCP client that is
explicitly configured with a FQDN MAY ignore the state of the "S" bit explicitly configured with a FQDN MAY ignore the state of the "S" bit
if the server's returned name matches the client's configured name. if the server's returned name matches the client's configured name.
4.3 Client Desires Server to Do DNS Updates 4.3. Client Desires Server to Do DNS Updates
A client can choose to delegate the responsibility for updating the A client can choose to delegate the responsibility for updating the
FQDN to IP address mapping for the FQDN and address(es) used by the FQDN to IP address mapping for the FQDN and address(es) used by the
client to the server. In order to inform the server of this choice, client to the server. In order to inform the server of this choice,
the client SHOULD include the Client FQDN option in its DHCPREQUEST the client SHOULD include the Client FQDN option in its DHCPREQUEST
message and MAY include the Client FQDN option in its DHCPDISCOVER. message and MAY include the Client FQDN option in its DHCPDISCOVER.
The "S" bit in the Flags field in the option MUST be 1. The "O" and The "S" bit in the Flags field in the option MUST be 1. The "O" and
"N" bits MUST be 0. "N" bits MUST be 0.
4.4 Client Desires No Server DNS Updates 4.4. Client Desires No Server DNS Updates
A client can choose to request that the server perform no DNS updates A client can choose to request that the server perform no DNS updates
on its behalf. In order to inform the server of this choice, the on its behalf. In order to inform the server of this choice, the
client SHOULD include the Client FQDN option in its DHCPREQUEST client SHOULD include the Client FQDN option in its DHCPREQUEST
message and MAY include the Client FQDN option in its DHCPDISCOVER. message and MAY include the Client FQDN option in its DHCPDISCOVER.
The "N" bit in the Flags field in the option MUST be 1 and the "S" The "N" bit in the Flags field in the option MUST be 1 and the "S"
and "O" bits MUST be 0. and "O" bits MUST be 0.
Once the client's DHCP configuration is completed (the client Once the client's DHCP configuration is completed (the client
receives a DHCPACK message and successfully completes a final check receives a DHCPACK message and successfully completes a final check
on the parameters passed in the message), the client MAY originate on the parameters passed in the message), the client MAY originate
its DNS updates provided the server's "N" bit is 1. If the server's its DNS updates provided the server's "N" bit is 1. If the server's
"N" bit is 0, the server MAY perform the PTR RR updates; and, MAY "N" bit is 0, the server MAY perform the PTR RR updates; and, MAY
also perform the A RR updates if the "S" bit is 1. also perform the A RR updates if the "S" bit is 1.
4.5 Domain Name and DNS Update Issues 4.5. Domain Name and DNS Update Issues
As there is a possibility that the DHCP server is configured to As there is a possibility that the DHCP server is configured to
complete or replace a domain name that the client sends, the client complete or replace a domain name that the client sends, the client
MAY find it useful to send the Client FQDN option in its DHCPDISCOVER MAY find it useful to send the Client FQDN option in its DHCPDISCOVER
messages. If the DHCP server returns different Domain Name data in messages. If the DHCP server returns different Domain Name data in
its DHCPOFFER message, the client could use that data in performing its DHCPOFFER message, the client could use that data in performing
its own eventual A RR update, or in forming the Client FQDN option its own eventual A RR update, or in forming the Client FQDN option
that it sends in its DHCPREQUEST message. There is no requirement that it sends in its DHCPREQUEST message. There is no requirement
that the client send identical Client FQDN option data in its that the client send identical Client FQDN option data in its
DHCPDISCOVER and DHCPREQUEST messages. In particular, if a client DHCPDISCOVER and DHCPREQUEST messages. In particular, if a client
skipping to change at page 10, line 38 skipping to change at page 10, line 38
used in the Client FQDN option in its DHCPDISCOVER or DHCPREQUEST, used in the Client FQDN option in its DHCPDISCOVER or DHCPREQUEST,
and MUST set the "E" bit in the option's Flags field accordingly. and MUST set the "E" bit in the option's Flags field accordingly.
If a client sends both the Client FQDN and Host Name option, the If a client sends both the Client FQDN and Host Name option, the
server SHOULD ignore the Host Name option. server SHOULD ignore the Host Name option.
The server SHOULD set the RCODE1 and RCODE2 fields to 255 before The server SHOULD set the RCODE1 and RCODE2 fields to 255 before
sending the Client FQDN message to the client in a DHCPOFFER or sending the Client FQDN message to the client in a DHCPOFFER or
DHCPACK. DHCPACK.
5.1 When to Perform DNS Updates 5.1. When to Perform DNS Updates
The server SHOULD NOT perform any DNS updates if the "N" bit is 1 in The server SHOULD NOT perform any DNS updates if the "N" bit is 1 in
the Flags field of the Client FQDN option in the DHCPACK messages (to the Flags field of the Client FQDN option in the DHCPACK messages (to
be) sent to the client. However, the server SHOULD delete any RRs be) sent to the client. However, the server SHOULD delete any RRs
which it previously added via DNS updates for the client. which it previously added via DNS updates for the client.
The server MAY perform the PTR RR DNS update (unless the "N" bit is The server MAY perform the PTR RR DNS update (unless the "N" bit is
1). 1).
The server MAY perform the A RR DNS update if the "S" bit is 1 in the The server MAY perform the A RR DNS update if the "S" bit is 1 in the
skipping to change at page 13, line 21 skipping to change at page 13, line 25
9. Acknowledgements 9. Acknowledgements
Many thanks to Mark Beyer, Jim Bound, Ralph Droms, Robert Elz, Peter Many thanks to Mark Beyer, Jim Bound, Ralph Droms, Robert Elz, Peter
Ford, Olafur Gudmundsson, Edie Gunter, Andreas Gustafsson, David W. Ford, Olafur Gudmundsson, Edie Gunter, Andreas Gustafsson, David W.
Hankins, R. Barr Hibbs, Kim Kinnear, Stuart Kwan, Ted Lemon, Ed Hankins, R. Barr Hibbs, Kim Kinnear, Stuart Kwan, Ted Lemon, Ed
Lewis, Michael Lewis, Josh Littlefield, Michael Patton, Jyrki Soini, Lewis, Michael Lewis, Josh Littlefield, Michael Patton, Jyrki Soini,
and Glenn Stump for their review and comments. and Glenn Stump for their review and comments.
10. References 10. References
10.1 Normative References 10.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Mockapetris, P., "Domain names - concepts and facilities", [2] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987. STD 13, RFC 1034, November 1987.
[3] Mockapetris, P., "Domain names - implementation and [3] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[4] Vixie, P., Thomson, S., Rekhter, Y. and J. Bound, "Dynamic [4] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic
Updates in the Domain Name System (DNS UPDATE)", RFC 2136, April Updates in the Domain Name System (DNS UPDATE)", RFC 2136,
1997. April 1997.
[5] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, [5] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997. March 1997.
[6] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G. and E. [6] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E.
Lear, "Address Allocation for Private Internets", BCP 5, Lear, "Address Allocation for Private Internets", BCP 5,
RFC 1918, February 1996. RFC 1918, February 1996.
[7] Stapp, M. and B. Volz, "Resolution of DNS Name Conflicts Among [7] Stapp, M. and B. Volz, "Resolution of DNS Name Conflicts Among
DHCP Clients (draft-ietf-dhc-ddns-resolution-*.txt)", September DHCP Clients (draft-ietf-dhc-ddns-resolution-*.txt)",
2004. September 2005.
10.2 Informative References 10.2. Informative References
[8] Marine, A., Reynolds, J. and G. Malkin, "FYI on Questions and [8] Marine, A., Reynolds, J., and G. Malkin, "FYI on Questions and
Answers - Answers to Commonly asked "New Internet User" Answers - Answers to Commonly asked "New Internet User"
Questions", RFC 1594, March 1994. Questions", RFC 1594, March 1994.
[9] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [9] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997. Extensions", RFC 2132, March 1997.
[10] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [10] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
RFC 2279, January 1998. RFC 2279, January 1998.
[11] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC 2671, [11] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC 2671,
 End of changes. 29 change blocks. 
52 lines changed or deleted 50 lines changed or added

This html diff was produced by rfcdiff 1.27, available from http://www.levkowetz.com/ietf/tools/rfcdiff/