Internet Architecture Board (IAB) K. Davies
Request for Comments: 9120
Nameservers for the Address and Routing Parameter Area ("arpa") Domain
This document describes revisions to operational practices to
separate the function of the "arpa" top-level domain in the DNS from
its historical operation alongside the DNS root zone.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Architecture Board (IAB)
and represents information that the IAB has deemed valuable to
provide for permanent record. It represents the consensus of the
Internet Architecture Board (IAB). Documents approved for
publication by the IAB are not candidates for any level of Internet
Standard; see Section 2 of RFC 7841
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9120
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Table of Contents 1.
Requirements for the "arpa" Zone 3.
Transition Process 3.1.
Dedicated Nameserver Hostnames 3.2.
Separation of Infrastructure 3.3.
Zone Administration 3.4.
Conclusion of Process 4.
IANA Considerations 5.
Security Considerations 6.
Normative References 6.2.
IAB Members at the Time of Approval
The "arpa" top-level domain [RFC3172
] is designated as an
"infrastructure domain" to support techniques defined by Internet
standards. Zones under the "arpa" domain provide various mappings,
such as IP addresses to domain names and E.164 numbers to URIs. It
also contains special-use names such as "home", which is a nonunique
name used in residential networks.
Historically, the "arpa" zone has been hosted on almost all of the
root nameservers (NSs), and [RFC3172
] envisages the "arpa" domain to
be "sufficiently critical that the operational requirements for the
root servers apply to the operational requirements of the "arpa"
servers". To date, this has been implemented by serving the "arpa"
domain directly on a subset of the root server infrastructure.
This bundling of root nameserver and "arpa" nameserver operations has
entwined management of the zones' contents and their infrastructures.
As a result, some proposals under consideration by the IETF involving
the "arpa" zone have been discarded due to the risk of conflict with
operations associated with managing the content of the root zone or
administering the root nameservers.
The separation described in this document resolves the operational
impacts of synchronizing edits to the root zone and the "arpa" zone
by eliminating the current dependency and allowing more tailored
operations based on the unique requirements of each zone.
2. Requirements for the "arpa" Zone
The "arpa" domain continues to play a role in critical Internet
operations, and this change does not propose weakening operational
requirements described in [RFC3172
] for the domain. Future
operational requirements for the "arpa" domain are encouraged to
follow strong baseline requirements such as those documented in
Changes to the administration of the "arpa" zone do not alter the
management practices of other zones delegated within the "arpa"
namespace. For example, "ip6.arpa" would continue to be managed in
accordance with [RFC5855
3. Transition Process
The process will dedicate new hostnames to the servers that are
authoritative for the "arpa" zone, but it will initially serve the
"arpa" zone from the same hosts.
Once completed, subsequent transitional phases could include using
new hosts to replace or augment the existing root nameserver hosts
and separating the editing and distribution of the "arpa" zone from
necessarily being connected to the root zone. Any future management
considerations regarding how such changes may be performed are beyond
the scope of this document.
3.1. Dedicated Nameserver Hostnames
Consistent with the use of the "arpa" namespace itself to host
nameservers for other delegations in the "arpa" zone [RFC5855
document specifies a new namespace of "ns.arpa", with the nameserver
set for the "arpa" zone to be initially labeled as follows:
Dedicated hostnames eliminate a logical dependency that requires the
coordinated editing of the nameservers for the "arpa" zone and the
root zone. This component of this transition does not require that
the underlying hosts that provide "arpa" name service (that is, the
root nameservers) be altered. The "arpa" zone will initially map the
new hostnames to the same IP addresses that already provide service
under the respective hostnames within "root-servers.net".
Because these nameservers are completely within the "arpa" zone, they
will require glue records in the root zone. This is consistent with
current practice and requires no operational changes to the root
3.2. Separation of Infrastructure
After initially migrating the "arpa" zone to use hostnames that are
not shared with the root zone, the underlying name service is
expected to evolve such that it no longer directly aligns with a
subset of root nameserver instances. With no shared infrastructure
between the root nameservers and the "arpa" nameservers, future novel
applications for the "arpa" zone may be possible.
Any subsequent change to the parties providing name service for the
zone is considered a normal management responsibility and would be
performed in accordance with [RFC3172
3.3. Zone Administration
Publication of the "arpa" zone file to the authoritative "arpa"
nameservers is currently undertaken alongside the root zone
maintenance functions. Upon the separation of the "arpa"
infrastructure from the root nameserver infrastructure, publication
of the "arpa" zone no longer necessarily needs to be technically
linked or interrelated to the root zone publication mechanisms.
3.4. Conclusion of Process
Full technical separation of operations of the "arpa" zone and root
zone minimally requires the following to be satisfied:
* The "arpa" zone no longer shares any hostnames in its nameserver
set with the root zone.
* The hosts that provide authoritative name service are not the same
hosts as the root nameservers, do not share any IPv4 or IPv6
addresses with the root servers, and are sufficiently provisioned
separately such that any unique "arpa" zone requirements can be
deployed without affecting how root zone service is provided.
* The editorial and publication process for the "arpa" zone removes
any common dependencies with the root zone process so that the
"arpa" zone can be managed, edited, and provisioned wholly
independently of the root zone.
Such separation is ultimately sought to allow for novel uses of the
"arpa" zone without the risk of inadvertently impacting root zone and
root server operations. It is recognized that achieving this state
requires a deliberative process involving significant coordination to
ensure impacts are minimized.
4. IANA Considerations
IANA shall coordinate the creation of the "ns.arpa" namespace and
populate it with address records that reflect the IP addresses of the
contemporary root servers documented within "root-servers.net" as its
initial state. The namespace may be provisioned either directly
within the "arpa" zone (as an empty nonterminal) or through
establishing a dedicated "ns.arpa" zone, according to operational
IANA will initially migrate the 12 NS records for the "arpa" zone to
point to their respective new entries in the "ns.arpa" domain.
When these actions are complete, the IAB and IANA will consult and
coordinate with all relevant parties on activity to reduce or
eliminate reliance upon the root zone and root server infrastructure
serving the "arpa" zone. Such changes will be performed in
compliance with [RFC3172
] and shall be conducted with all due care
and deliberation to mitigate potential impacts on critical
5. Security Considerations
The security of the "arpa" zone is not necessarily impacted by any
aspects of these changes. Robust practices associated with
administering the content of the zone (including signing the zone
with DNSSEC) as well as its distribution will continue to be
6.1. Normative References
] Huston, G., Ed., "Management Guidelines & Operational
Requirements for the Address and Routing Parameter Area
Domain ("arpa")", BCP 52, RFC 3172
, DOI 10.17487/RFC3172
September 2001, <https://www.rfc-editor.org/info/rfc3172
6.2. Informative References
] Abley, J. and T. Manderson, "Nameservers for IPv4 and IPv6
Reverse Zones", BCP 155, RFC 5855
, DOI 10.17487/RFC5855
May 2010, <https://www.rfc-editor.org/info/rfc5855
] Blanchet, M. and L-J. Liman, "DNS Root Name Service
Protocol and Deployment Requirements", BCP 40, RFC 7720
, December 2015,
IAB Members at the Time of Approval
Internet Architecture Board members at the time this document was
approved for publication were:
Thank you Alissa Cooper, Michelle Cotton, Lars-Johan Liman, Wes
Hardaker, Ted Hardie, Paul Hoffman, Russ Housley, Oscar Robles-Garay,
Duane Wessels, and Suzanne Woolf for providing review and feedback.
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