draft-ietf-ipv6-dns-discovery-04.txt   draft-ietf-ipv6-dns-discovery-05.txt 
Network Working Group Alain Durand
INTERNET-DRAFT SUN Microsystems, inc.
June 14, 2002 Jun-ichiro itojun Hagino
Expires December 2002 IIJ Research Laboratory
Dave Thaler
Microsoft
Network Working Group Dave Thaler Well known site local unicast addresses for DNS resolver
INTERNET-DRAFT Microsoft <draft-ietf-ipv6-dns-discovery-05.txt>
March 1, 2002 Jun-ichiro itojun Hagino
Expires August 2002 IIJ Research Laboratory
IPv6 Stateless DNS Discovery
<draft-ietf-ipv6-dns-discovery-04.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
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Abstract Abstract
This document specifies the steps a host takes in deciding how to This documents specifies a method for nodes to find a DNS resolver
autoconfigure the addresses of DNS Servers required for name with minimum configuration in the network and without running a
resolution in IP version 6. The autoconfiguration process discovery protocol on the nodes.
includes determining whether such information should be obtained
through the stateless mechanism, the stateful mechanism, or both.
This document defines the process for acquiring a list of DNS
server addresses. Approaches for acquiring a domain search path,
and the domain name of the host via a stateless mechanism are
Draft Stateless DNS Discovery March 2002
included in an appendix for further study. The details of
autoconfiguration using the stateful protocol are specified
elsewhere.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
Draft Stateless DNS Discovery March 2002
1. Introduction 1. Introduction
RFC 2462 [ADDRCONF] specifies "OtherConfigFlag" as a per-interface RFC 2462 [ADDRCONF] provides a way to autoconfigure nodes with one or
variable, which is set from the value of the "O" ("Other stateful more IPv6 address and default routes.
configuration") flag in Router Advertisements received. When
OtherConfigFlag is set on an interface, information related to
name resolution is obtained using the stateful autoconfiguration
mechanism. However, when OtherConfigFlag is not set, it does not
describe how to obtain such information. This is the purpose of
this document.
For a host to effectively resolve names of other hosts, and
potentially allow resolution of its name to be performed, the
following parameters are typically required:
o One or more addresses of Domain Name Service (DNS) [RFC1034,
RFC1035] servers. The function of name-to-address resolution
(or vice versa) in IP is performed by DNS, which requires that
at least one DNS Server be known and reachable by a device
desiring to perform name resolution.
o A per-interface domain name of the host itself, and is
equivalent to the Domain Name option in [DHCP]. This can be
used when Multicast DNS is enabled, and the host responds to
queries for its own name, as well as when DNS Dynamic Update is
enabled. Depending on the implementation, the per-interface
domain name may or may not be the same thing as the primary
domain name of the host.
o Search path. It is currently common practice for the search
path to be computed by a device based on its domain name(s).
However, a DHCP option [DOMSEARCH] has been proposed, and so
search path configuration is likely to be a requirement in
general.
o mDNS-enabled flag. This parameter controls whether Multicast
DNS [MDNS] should be enabled on the host's interface.
A design team recommendation [DDDT] contains an analysis of the
requirements and solution space, which was used as the basis for
this document. One result of this analysis was that there is a
spectrum of configuration/discovery mechanisms. At one end, a
single protocol is used to configure/discovery all types of
information. This style works well in an administered environment
where a network administrator wants to have a central point of
Draft Stateless DNS Discovery March 2002
control, and apply policies, etc. At the other end, each protocol
is self-configuring, rather than depending on any other protocol
or server. This style provides optimal fate sharing, and works
well in zero-configuration environments such as adhoc networks and
simple networks without network administrator staff. The former
mechanism is used with the "Other stateful configuration" flag is
used, and this draft provides the benefits (and limitations) of
the latter approach when "Other stateful configuration" is not
set.
Note: This document only includes in its body a solution for
obtaining the address of Domain Name Service servers. Mechanisms
for obtaining the other parameters listed above are included in an
Appendix A for further study. These may be moved to a separate
document in the future.
2. Overview
A set of three well-known site-local IPv6 addresses are reserved
for autodiscovery of DNS servers. These addresses may be used as
unicast addresses assigned to different servers. The use of the
addresses as anycast addresses with one of them being assigned to
all DNS servers in the site, or any combination of anycast and
unicast addresses, is for further study.
Host routes for these addresses are propagated in the site's
routing tables. This document proposes that these three addresses
be:
fec0:0:0:ffff::1
fec0:0:0:ffff::2
fec0:0:0:ffff::3
This list of three addresses may be hardcoded into a host.
Furthermore, we define two levels of functionality. Level 1 is
defined below. Level 2 is described in Appendix A and is for
further study.
Draft Stateless DNS Discovery March 2002
3. Level 1 Compliance
Level 1 compliance entails using the three addresses above for
actual name resolution. It provides only rudimentary
functionality. In particular, it does not provide the ability to
have separate configuration for hosts on different subnets, nor to
provide hosts with a domain name other than one for which the DNS
server is authoritative.
3.1. DNS Server Configuration
Level 1 functionality requires no DNS server configuration other
than assigning one of the well-known addresses to one of the
server's interfaces. A host route must then be injected into the
routing domain, e.g., by configuring a static host route on the
server's router, and redistributing it into the intra-domain
routing protocol.
A host route must then be injected into the site's routing
infrastructure. Route injection can be done via any of several
methods, including but not limited to:
a) Run the server on a router, and configure it to inject the host
route.
b) Run a routing protocol on the server, and configure it to
inject the host route. Note that this requires that the server
and its router(s) must run the same routing protocol, at least
for communication between the router(s) and the server(s) on
the link. However, a server does not need to participate fully
in the routing protocol, it only needs to be able to inject
routes.
c) Run multiple servers on the same link(s), and configure their
local router(s) to inject host routes for the well-known
address into the site's routing infrastructure. Running
multiple servers on the same link provides robustness to the
failure of a server, while routing provides robustness to the
loss of routers and other links. There may still be some
failures, however, such as a unidirectional failure of the
router's interface, which are not handled by this option.
d) Modify the routers on the link to periodically solicit (using
Neighbor Discovery) the well-known address, and inject the
Draft Stateless DNS Discovery March 2002
host route based on whether a reply is received. However, for a node to be fully operational on a network, many other
parameters are needed, such as the address of a DNS resolver, mail
relays, web proxies, etc. Except for name resolution, all the other
services are usually described using names, not addresses, such as
smtp.myisp.net or webcache.myisp.net. For obvious bootstrapping
reasons, a node needs to be configured with the IP address (and not
the name) of a DNS resolver. As IPv6 addresses look much more
complex than IPv4 ones, there is some incentive to make this
configuration as automatic and simple as possible.
3.2. Host Behavior Although it would be desirable to have all configuration parameters
configured/discovered automatically, it is common practice in IPv4
today to ask the user to do manual configuration for some of them by
entering server names in a configuration form. So, a solution that
will allow for automatic configuration of the DNS resolver is seen as
an important step forward in the autoconfiguration story.
The host sets its DNS server list equal to the set of three The intended usage scenario for this proposal is a home or enterprise
addresses listed above. The search path is not discovered, but is network where IPv6 nodes are plugged/unplugged with minimum
generated from the host's domain name(s) as is currently common management and use local resources available on the network to
practice. If desired, a per-interface domain name can be obtained autoconfigure. This proposal is also usefull in cellular networks
by sending a query (with the Recursion Desired (RD) bit set), where all moble devices are included within the same site.
doing a reverse lookup for the well-known site-local IPv6
destination address, and extracting the domain name from the NS
record in the reply.
4. Security Considerations 2. Pre-configuration vs discovery
Ensuring that queries reach a legitimate DNS server relies on the Some of the discussions in the past around DNS server discovery have
security of the IPv6 routing infrastructure. The issues here are been trying to characterize the solution space into stateless versus
the same as those for protecting basic IPv6 connectivity. stateful or server-oriented versus severless. It is not absolutely
clear how much state if any needs to be kept to perform DNS server
discovery, and, although the semantic differences between a router
and a server are well understood from a conceptual perspective, the
current implementations tend to blur the picture. In another attempt
to characterize different approaches, one can look at how much
intelligence a client needs to have in order to use the service.
IPsec/IKE can be used when the well-known addresses are used as One avenue is to ask the IPv6 node to participate in a discovery
unicast addresses. protocol, such as SLP or DHCP, learn the address of the server and
send packets to this server. Another one is to pre-configure (hard-
code) a local scope address on the IPv6 node and let it send packets
directly to this address, with the underlying assumption that the
routing system will forward them to the right place. This document
explores this later avenue of pre-configuration that does not require
participation of the end node in the DNS resolver discovery
mechanism.
The payload can be protected as follows. If the client can The mechanism described here is to be used as a last resort, when no
preconfigure a well known private or public key then TSIG [TSIG] other configuration information is available.
can be used with the same packets presented for the query. If
this is not the case, then TSIG keys will have to be negotiated
using [TKEY]. After the client has the proper key then the query
can be performed.
5. IANA Considerations 3. Reserved Prefix and addresses
The IANA should assign the following site-local IPv6 addresses to The basic idea of this proposal is to reserve a well known IPv6 site
be used as well-known addresses assigned to DNS servers: local prefix and three well known IPv6 addresses for DNS resolvers
and then have the routing system forward the DNS request to those DNS
resolvers.
fec0:0:0:ffff::1 IPv6 nodes will be pre-configured (hard coded) with those three IPv6
fec0:0:0:ffff::2 addresses as DNS resolver.
fec0:0:0:ffff::3.
[Note to readers: the above addresses are tentative, but the ffff Each local DNS resolvers should be configured with one of those three
is intended to be consistent with a simultaneous proposal to addresses to enable clients to switch from one to the other if one
reserve the ffff SLA for use with IANA-assigned addresses such as fails. Host routes for each of those resolvers should be injected in
these.] the local routing system. Example methods for injecting host routes
and a brief discussion of their fate sharing properties is presented
here:
Draft Stateless DNS Discovery March 2002 a) Manual injection of routes by a router on the same subnet.
If the node running the DNS resolver goes down, the router may or
may not be notified and keep announcing the route.
6. Acknowledgements b) Running a routing protocol on the same node running the DNS
resolver.
If the process running the DNS resolver dies, the routing protocol
may or may not be notified and keep annoucing the route.
The IPv6 DNS Discovery Design Team [DDDT] provided recommendations c) Running a routing protocol within the same process running the
that formed the basis of this specification. Rob Austein and the DNS resolver.
IPv6 Working Group provided valuable feedback on the mechanism. If the DNS resolver and the routing protocol run in separated
Aaron Schrader provided helpful comments as well. Robert Hinden threads, similar concerns as above are true.
edited this version of the document.
7. References d) Having an "announcement" protocol that the DNS resolver could
use to advertize the host route to the nearby router.
Details of such a protocols are out of scope of this document, but
something similar to [MLD] is possible.
[ADDRCONF] IANA considerations for this prefix are covered in Section 6.
Thomson, S., and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[ANYCAST] 4. Site local versus global scope considerations
Hagino, Jun-ichiro itojun, and K. Ettikan, "An analysis of
IPv6 anycast", draft-ietf-ipngwg-ipv6-anycast-
analysis-00.txt, Work in progress, July 2001.
[DDDT] The rationales for having a site local prefix are:
Thaler, D., Editor, "Analysis of DNS Server Discovery
Mechanisms for IPv6", draft-ietf-ipngwg-dns-discovery-
analysis-00.txt
[DIFFSEC] -a) Using a site local prefix will ensure that the traffic to the
D. Eastlake, "Storage of Diffie-Hellman Keys in the Domain DNS resolver stays local to the site. This will prevent the DNS
Name System (DNS)", RFC 2539, March 1999. requests from accidentally leaking out of the site. However, the
local resolver can implement a policy to forward DNS resolution of
non-local addresses to an external DNS resolver.
[DNSSEC] -b) Reverse DNS resolution of site local addresses is only
D. Eastlake, "Domain Name System Security Extensions", RFC meaningful within the site. Thus, making sure that such queries
2535, March 1999. are first sent to a DNS resolver located within the site perimeter
increase their likelyhood of success.
[DOMSEARCH] Note: there is currently some discussions about the usefulness of
B. Aboba, "DHCP Domain Search Option", draft-aboba-dhc- site local addresses in the IPv6 architecture. Depending on the
domsearch-01.txt, December 2000. outcome of this discussion, this section will need to be revisited.
If a global prefix was chosen for this mechanism, concerns raised in
a) could be addressed using a simple access list on the site exit
routers and concerns raised in b) would disappear.
[MDNS] 5. Examples of use
Esibov, L., Aboba, B., and D. Thaler, draft-ietf-dnsext-
mdns-03.txt, July 2001.
[TKEY] This section presents example scenarios showing how the mechanism
D. Eastlake, "Secret Key Establishment for DNS (TKEY RR)" RFC described in this memo can co-exist with other techniques, namely
2930, September 2000. manual configuration and DHCPv6 discovery.
Draft Stateless DNS Discovery March 2002 5.1 Simple case, general purpose DNS resolver
[TSIG] This example shows the case of an enterprise or a cellular network
Vixie, P., Gudmundsson, O., Eastlake, D. and B. Wellington, that manages a full flavor general purpose DNS resolver and a large
"Secret Key Transaction Authentication for DNS (TSIG)", RFC number of nodes running DNS stub resolvers. The DNS resolver is
2845, May 2000. performing (and caching) all the recursive queries on behalf of the
stub resolvers. Those stub resolvers are either manually configured
with the IPv6 address of the resolver or with one (or several) of the
well known site local unicast addresses defined in this memo.
8. Authors' Addresses -------------------------------------------
| |
| --------------------- |
| |manually configured| |
| |DNS stub resolver | |
| --------------------- |
| ---------- | |
| |DNS |<----------- |
| |resolver|<----------- |
| ---------- | |
| --------------------- |
| |DNS stub resolver | |
| |configured with | |
| |well known address | |
| --------------------- |
| |
-------------------------------------------
Dave Thaler (The DNS resolver is configured to listen both on
Microsoft its IPv6 address and on the well known address)
One Microsoft Way
Redmond, CA 98052, USA
Email: dthaler@microsoft.com
Jun-ichiro itojun HAGINO 5.2 DNS forwarder
Research Laboratory, Internet Initiative Japan Inc.
Takebashi Yasuda Bldg.,
3-13 Kanda Nishiki-cho,
Chiyoda-ku, Tokyo 101-0054, JAPAN
Email: itojun@iijlab.net
Draft Stateless DNS Discovery March 2002 A drawback of the choice of site local scope for the reserved
addresses for DNS resolver is that, in the case of a home/small
office network connected to an ISP, DNS traffic cannot be sent
directly to the ISP DNS resolver without having the ISP and all its
customers share the same definition of site.
9. Appendix A - Level 2 Compliance In this scenario, the home/small office network is connected to the
ISP router (PE) via an edge router (CPE). Prefix delegation is
performed out of band is is out of scope of this memo.
Level 2 compliance allows site administrators to have site-wide -------------
defaults for all name resolution parameters, and optionally to / |
have subnet-specific overrides. However, it defines a new DNS -------- -------------- / |
record type to hold name resolutioin configuration information. |ISP PE| |customer CPE| / Customer |
In this way, DNS becomes self-configuring. | |===========| |====< site |
| | | | \ |
-------- -------------- \ |
\ |
-------------
9.1. DNS Server Configuration The customer router CPE could be configured on its internal interface
with one of the reserved site local addresses and listen for DNS
queries. It would be configured to use one (or several) of the well
known site local unicast addresses within the ISP's site to send its
own queries to. It would act as a DNS forwarder, forwarding queries
received on its internal interface to the ISP's DNS resolver.
A new record type, CFG, is defined, with a syntax as follows: -------------
<owner> <class> <ttl> CFG "<attribute name>=<attribute value>" / |
---------- -------------- / |
|ISP | |customer CPE| / Customer |
|DNS |===========| DNS|====< site |
|resolver| <------|---forwarder|-----\---- |
---------- -------------- \ |
\ |
-------------
The set of attribute names is described below. This set may be In this configuration, the CPE is acting as a multi-sited router.
extended by other RFCs, but any new attributes MUST be specific to
name resolution.
The DNS server list is expressed with a string of the form 5.3 DNS forwarder with DHCPv6 interactions
"dnsservers=<address>[,<address>]*" where the attribute value is a
comma-separated list of one or more addresses (either IPv4 or
IPv6) in string literal format suitable for passing to
getaddrinfo.
The domain name to use is expressed with a string of the form In this variant scenario, DHCPv6 could be used between the PE and CPE
"domainname=<domain>" where the attribute value is the domain name to do prefix delegation [DELEG] and DNS resolver discovery.
the client should use.
The domain suffix search path is expressed with a string of the -------------
form "searchpath=<domain>[,<domain>]*" where the attribute value / |
is a comma-separated list of domain suffixes. -------- -------------- / |
|ISP | |customer CPE| / Customer |
|DHCPv6|===========| DHCPv6|====< site |
|server| <------|------client| \ |
-------- -------------- \ |
\ |
-------------
The mDNS enabled flag is expressed with a string of the form This example will show how DHCPv6 and well known site local unicast
"mdnsenabled=<value>" where the attribute value is either "true" addresses can be used at the same time within a site to discover the
or "false". address of the DNS forwarder.
Name resolution information can be expressed as defaults for the The customer router CPE could be configured on its internal interface
entire site, as well as per-subnet overrides if desired. To with one of the reserved site local addresses and listen for DNS
express site defaults, the record owner used is a wildcard, namely queries. It would act as a DNS forwarder, forwarding those queries to
*.local.arpa. The format of per-subnet overrides is described in the DNS resolver pointed out by the ISP in the DHCPv6 exchange.
the next section.
[NOTE WELL: the use of "local.arpa" and the CFG record syntax -------------
shown above are just placeholders until DNS experts figure out / |
what the right thing is.] ---------- -------------- / |
|ISP | |customer CPE| / Customer |
|DNS |===========| DNS|====< site |
|resolver| <------|---forwarder|-----\---- |
---------- -------------- \ |
\ |
-------------
Draft Stateless DNS Discovery March 2002 The same CPE router could also act as a local DHCPv6 server,
advertising either itself as DNS forwarder.
Each of the attributes described herein are optional, and any -------------
combination may be used, except that only one record per / |
attributename should be present per owner (site or subnet) string. -------- -------------- / Customer |
|ISP PE| |customer CPE| / site |
| |===========|DHCPv6 |====< |
| | |server------|-----\---> |
-------- -------------- \ |
\ |
-------------
*.local.arpa IN CFG "dnsservers=fec0:0:1::1,fec0:0:2::2" Within the site:
*.local.arpa IN CFG "domainname=example.com"
*.local.arpa IN CFG "searchpath=foo.example.com,
bar.example.com,example.com"
*.local.arpa IN CFG "mdnsenabled=true"
Table 1: Example configuration a) DHCPv6 aware clients could use DHCPv6 to obtain the address of
the DNS forwarder...
The DNS server must also be assigned one of the well-known site- -------------
local addresses, and a host route must be injected into the site's / |
routing infrastructure, e.g. using one of the methods described ---------- -------------- / Customer |
above in Section 3.1. |ISP | |customer CPE| / site |
|DNS |===========| DNS|====< |
|resolver| <------|---forwarder|-----\----DHCPv6 |
---------- -------------- \ client |
\ |
-------------
(The address of the DNS forwarder is aquired via DHCPv6.)
9.2. Host Behavior b) other nodes may simply send their DNS request to the reserved
site local addresses.
When an interface comes up, and a host determines that the -------------
OtherConfigFlag on the interface is off, then it takes the / |
following actions. ---------- -------------- / customer |
|ISP | |customer CPE| / site |
|DNS |===========| DNS|====< |
|resolver| <------|---forwarder|-----\----non DHCPv6|
---------- -------------- \ node |
\ |
-------------
(Internal nodes use the reserved site local unicast address.)
The host constructs a DNS query for CFG records for A variant of this scenario is the CPE can decide to pass the global
"<subnet>.local.arpa.", where <subnet> is constructed from an address of the ISP DNS resolver in the DHCPv6 exchange with the
onlink prefix as follows: internal nodes.
1) Determine the onlink prefix to use. Any onlink site-local 6. IANA considerations
prefix is used, if present. Otherwise, any onlink global
prefix is used. If no other onlink prefixes are present (e.g.,
if no routers are present), the link-local prefix is used as a
last resort.
2) Convert the subnet prefix to a string by taking the lower case The site local prefix fec0:0000:0000:ffff::/64 is to be reserved out
string literal representation, with no zero compression, and of the site local fec0::/10 prefix.
replacing all colons with underscores. Table 2 below shows
some examples. This notation is used so that it uses only one
token, is unique per prefix, and is human readable.
Draft Stateless DNS Discovery March 2002 The unicast addresses fec0:000:0000:ffff::1, fec0:000:0000:ffff::2
and fec0:000:0000:ffff::2 are to be reserved for DNS resolver
configuration.
Prefix String All other addresses within the fec0:0000:0000:ffff::/64 are reserved
fec0:0:0:1::/64 fec0_0000_0000_0001.local.arpa for future use and are expected to be assigned only with IESG
3ffe:ffff:0:1234::/64 3ffe_ffff_0000_1234.local.arpa approval.
fe80::/64 fe80_0000_0000_0000.local.arpa
Table 2: Example queries 7. Security Considerations
Once the query is formed, the host initially sends out the query Ensuring that queries reach a legitimate DNS server relies on the
using UDP to each discovery address in turn until a reply is security of the IPv6 routing infrastructure. The issues here are the
received, or until the end of the list is reached. To avoid same as those for protecting basic IPv6 connectivity.
implosion problems when an entire site reboots such as after a
power outage, the first request should wait 3 seconds for a reply,
with the wait period doubling for each subsequent request.
Since the destination address may be an anycast address, the reply IPsec/IKE can be used as the well-known addresses are used as unicast
will necessarily come from a different address. The host must not addresses.
discard the reply simply because the source address is different.
A more detailed discussion of this issue can be found in
[ANYCAST].
Upon receiving a response, the host parses the CFG records and The payload can be protected using standard DNS security techniques.
acts on the information as follows. If the client can preconfigure a well known private or public key
then TSIG [TSIG] can be used with the same packets presented for the
query. If this is not the case, then TSIG keys will have to be
negotiated using [TKEY]. After the client has the proper key then
the query can be performed.
If a dnsservers attribute is present, the list of server addresses The use of site local addresses instead of global addresses will
is extracted from the value. If no such attribute is present (or ensure the DNS queries issued by host using this mechanism will not
if no reply is received), an implementation-specific default list leak out of the site.
is used. For example:
o an implementation MAY use an empty list (effectively 8. References
disabling name resolution),
o a host MAY use a DNS server list containing only the anycast [ADDRCONF]
address, subject to the limitations discussed in the next Thomson, S., and T. Narten, "IPv6 Stateless Address
section, Autoconfiguration", RFC 2462, December 1998.
o a host MAY use mDNS [MDNS] only, or [MLD]
Deering, S., Fenner, W., Haberman, B.,
"Multicast Listener Discovery (MLD) for IPv6",
RFC2710, October 1999.
o a host MAY use some combination of the above. [TSIG]
Vixie, P., Gudmundsson, O., Eastlake, D. and B. Wellington,
"Secret Key Transaction Authentication for DNS (TSIG)",
RFC2845, May 2000.
In general, the list obtained is used in the same way as if the [TKEY]
list had been obtained (or failed to be obtained) via DHCP. D. Eastlake, "Secret Key Establishment for DNS (TKEY RR)",
RFC2930, September 2000.
If a domainname attribute is present, the domain name is extracted [DHCPv6]
Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and
Droms, R. (ed.), "Dynamic host Configuration Protocol for IPv6
(DHCPv6)", draft-ietf-dhc-dhcpv6-23 (work in progress),
Februray 2002.
Draft Stateless DNS Discovery March 2002 [DELEG]
Troan, O., Droms, R., "IPv6 Prefix Options for DHCPv6",
draft-troan-dhcpv6-opt-prefix-delegation-00.txt (work in progress),
February 2002.
from the value. The domain name (or lack thereof) is used in the 9. Authors' Addresses
same way as if the list had been obtained (or failed to be
obtained) via DHCP.
If the searchpath attribute is present, the search path is Alain Durand
extracted from the value. If not present, the host uses the SUN microsystems, inc.
search path it would use if no path had been obtained if DHCP were 901 San Antonio rd UMPK 17-202
in use. Palo Alto, CA 94303, USA.
Email: Alain.Durand@sun.com
If the mdnsenabled attribute is present, the value is extracted. Jun-ichiro itojun HAGINO
If not present, mDNS is not enabled. Research Laboratory, Internet Initiative Japan Inc.
Takebashi Yasuda Bldg.,
3-13 Kanda Nishiki-cho,
Chiyoda-ku, Tokyo 101-0054, JAPAN
Email: itojun@iijlab.net
Draft Stateless DNS Discovery March 2002 Dave Thaler
Microsoft
One Microsoft Way
Redmond, CA 98052, USA
Email: dthaler@microsoft.com
10. Full Copyright Statement 10. Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished This document and translations of it may be copied and furnished to
to others, and derivative works that comment on or otherwise others, and derivative works that comment on or otherwise explain it
explain it or assist in its implementation may be prepared, or assist in its implementation may be prepared, copied, published
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 End of changes. 

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