Internet DRAFT - draft-kurtis-tld-ops
draft-kurtis-tld-ops
DNSOP K. Lindqvist
Internet-Draft Netnod Internet Exchange
Expires: December 3, 2005 June 2005
Operation of TLD zones
draft-kurtis-tld-ops-00.txt
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Copyright (C) The Internet Society (2005).
Abstract
The Internet is today the defacto standard packet network for a lot
of critical communications. The Internet in turn have a heavy
dependency on the Domain Name System (DNS) for it's "normal"
operations. The IETF in June 2000 described the operating
requirements [1]for the so called root-servers that defines the root
of the DNS lookup tree. Similar requirements could where deemed
needed be applied to DNS infrastructure at other levels of the DNS
tree as well. This document analyses these requirements and what can
be done to ensure a reliable DNS infrastructure.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use of this document . . . . . . . . . . . . . . . . . . . . . 3
4. Analysis of requirements . . . . . . . . . . . . . . . . . . . 4
5. Operational requirements . . . . . . . . . . . . . . . . . . . 4
5.1 Slave server operations . . . . . . . . . . . . . . . . . 4
5.1.1 Location . . . . . . . . . . . . . . . . . . . . . . . 4
5.1.2 Physical requirements . . . . . . . . . . . . . . . . 4
5.1.3 Software requirements . . . . . . . . . . . . . . . . 5
5.1.4 Protocol requirements . . . . . . . . . . . . . . . . 5
5.2 Slave server infrastructure . . . . . . . . . . . . . . . 6
5.2.1 Dimensioning the infrastructure . . . . . . . . . . . 6
5.2.2 Following common practice . . . . . . . . . . . . . . 6
5.3 Registry operations . . . . . . . . . . . . . . . . . . . 7
5.3.1 Registry/Registrar interface . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Protocol Considerations . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . 9
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1. Introduction
The Internet is today the defacto standard packet network for a lot
of critical communications. The Internet in turn have a heavy
dependency on the Domain Name System (DNS) for it's "normal"
operations. The IETF in June 2000 described the operating
requirements [1]for the so called root-servers that defines the root
of the DNS lookup tree. So far though, operational requirements of
the second tier of the DNS has not been defined. This document tries
to analyze and define the operational requirements for the second
tier in the DNS lookup hierarchy.
The second tier infrastructure in the DNS is called the Top Level
Domains (TLDs). These include both generic TLDs (gTLDs) such as .com
and .info and country code TLDs (ccTLDs). In the hierarchy
immediately under the TLDs, we will have either directly registered
domain names in use by an entity for lookup of their services and
host names. Alternatively we will find a third their hierarchy
grouping the same type of names, for example edu.uk for educational
institutions in the UK, and co.uk for commercial companies in the UK.
The latter method is mostly used to provide better scaling for the
TLD. In this case this document would be applicable to both the
second and the third tier.
The service level experience of the end-user with regard to DNS is
dependent on several levels of hierarchy. Usually each level will be
the responsibility of multiple entities, such as the root-server
operators, the TLD slave-server operators and the operator of the
actual leaf zone. The weakest operation in that chain can make the
service unreachable and result in a failure for an end node trying to
access a particular service address, or host name. The root-server
operations are as noted earlier described in an IETF/RFC. This
document tries to outline the same requirements for the TLDs. This
leaves the operator of the leaf zone. This document should however
also provide useful information for operators of leaf zones, but some
of the requirements may be considered to strict for most leaf zones.
2. Terminology
Service Address: an IP address associated with a particular service
(e.g. the address of a nameserver).
3. Use of this document
While this document provides for a set of operational requirements
for a TLD, they are not to be taken as absolute requirements. Needs
and capabilities of TLDs will vary over the different operational
aspects in this document. Some of them are still to be considered as
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minimal requirements, the slave-server operations, registry
operations and protocol requirements.
This document is not to been seen as an absolute requirements
document, but rather as a check-list for TLD registrars, registries
and TLD slave-server operators. The intent is also no to try and
"score" the various requirements. The priority among them will vary
very much between different TLDs and uses.
4. Analysis of requirements
The requirements in this document are targeting maximum operational
stability, security and resilience for a TLD operation. This
reflects the critical dependency many systems today have on the
Internet, and the role the DNS has come to play. The requirements
are not targeting business practices, or take into account
affordability or need. This analysis is left to the users and
readers of this document.
5. Operational requirements
5.1 Slave server operations
5.1.1 Location
The ideal location of slave-servers can be broken down into two sub-
categories. The ideal physical location, which is discussed in
Section 5.1.2, and location in the network topology.
Finding the ideal location for the TLD slave-servers in the topology
is a complex analysis. Factors that should be taken into account are
o Ensure optimal performance for the target community (such as a
particular country for a ccTLD). I.e try to be as topologically
close to the largest user base as possible.
o The slave servers should be as topologically diverse as is
feasible to avoid a infrastructure problem taking out one or more
of the servers.
o Locating slave-servers where they will have the best and easiest
access to a large number of networks will provide better
performance and give more networks shorter and more direct access
to the data.
5.1.2 Physical requirements
The location of the slave-servers should meet co-location industry
standards with regard to the physical environment. This includes
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Redundant power feeding: The servers should be located so that a
single interrupt of power into the site where these are located
does not effect the servers, or the network infrastructure
servicing the slave-servers.
Cooling: The site should provide adequate and redundant cooling that
also operates adequately in the event of a power failure.
Access: The physical location should have restricted access, and only
allow required operational staff to gain physical and control of
the slave-servers.
Fire supresssion: The physical location should provide adequate fire
fighting and/or suppression equipment.
5.1.3 Software requirements
The slave-servers should be held to normal industry standards. This
includes standard operational practices as
Patches: The server operating system and software should be kept
uptodate with the most recent security patches for the software.
Backups: The slave-server systems should be backed up regularly.
This includes zone data, system configurations and other data and
configurations needed for a quick system recovery in the case of a
failure. The procedures and systems for backup should be tested
for resteration regularly.
Capacity: The system software should be otpimally tuned to serve the
requirements of the zone in question. The system should be able
to handle at least three times the normal load of questions per
seconds.
Remote management: The server system should allow for secure,
encrypted and authenticated remote management.
Time syncronization: Servers should for accuracy of logging have
their clocks syncronized using the Network Time Protocol [2].
5.1.4 Protocol requirements
The slave-servers must be running software that supports the current
set of DNS protocol standards (as of writing RFC1034 [3],RFC1035
[4],RFC2181 [5]. For TLDs that are claiming Secure DNS support, the
server software also should support RFC4033 [6],RFC4034 [7], RFC4035
[8].
In addition to supporting the above protocol standards there are also
a number of configuration parameters the slave-service should follow.
These are
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Recursion: The slave-service should not be providing recursive name-
service.
In-Bailiwick-glue: The zone should be configured to use "In-
Bailiwick-glue", as that will give the TLD operator full control
over the entire delegation chain and give the TLD operational
control over the stability of the service.
Limited service The TLD slave-service should not at the same time be
authorative for relatives (lower tiers) to the TLD zone. This
avoids collapsing signed delegation data when DNSSEC is used.
5.2 Slave server infrastructure
A critical factor in guaranteeing the stability, resilience and
redundancy of the TLD slave-service is the network infrastructure
that connects the physical servers. With the increase in Distributed
Denial of Service(DDoS) attacks, this is also an increasing area of
concerns for TLD operators. Configuring and dimensioning the network
infrastrucutre is therefor becoming inreasingly important for the TLD
operator.
5.2.1 Dimensioning the infrastructure
The network infrastructure should be dimensioned to handle a network
load of three times the normal load, measured in packets-per-seconds,
pps. The infrastructure should also be able of dropping packets at
line-rate in order to protect the service in the case of an attack.
What "line-rate" corresponds to in absolute numbers is depending on
local conditions, such as affordability, need and uplink speeds.
5.2.2 Following common practice
The network infrastructure fronting the slave-service should be
configured accoring to normal industry practice. This includes at a
minimum
Network separation: The network connection should not be shared with
other, non-trusted hosts. In other words, the connection should
be provided on a switched or routed infrastructure to avoid
wiretapping and/or spoofing of packets.
Ingress filtering: The network infrastructure should filter out
spoofed packets using the methods descibed in RFC3704/BCP84 [9].
Network protection: The infrastructure should apply some form of
packet filtering methods that only allows traffic to ports needed
for the service and management traffic from well-known management
networks if needed.
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Network security: The network infrastructure should be configured
accoring to industry standard, for example as described in
FILL_IN. The network infrastructure should also onyl be remotly
and physically accessiable by operational staff. Remote access
must be authenticated and encrypted.
5.3 Registry operations
5.3.1 Registry/Registrar interface
FILL_IN perhaps some text on EPP etc.
6. Security Considerations
7. Protocol Considerations
This document does not impose any protocol considerations.
8. IANA Considerations
This document requests no action from IANA.
9. Acknowledgements
The following people have contributed to this document: David Meyer,
Peter Koch, Johan Ihren, Patrik Falstrom. The author would like to
extend great appreciation to them for the reviews, and text they have
contributed with.
10. References
[1] Bush, R., Karrenberg, D., Kosters, M., and R. Plzak, "Root Name
Server Operational Requirements", BCP 40, RFC 2870, June 2000.
[2] Mills, D., "Network Time Protocol (Version 3) Specification,
Implementation", RFC 1305, March 1992.
[3] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[4] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[5] Elz, R. and R. Bush, "Clarifications to the DNS Specification",
RFC 2181, July 1997.
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[6] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"DNS Security Introduction and Requirements", RFC 4033,
March 2005.
[7] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"Resource Records for the DNS Security Extensions", RFC 4034,
March 2005.
[8] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"Protocol Modifications for the DNS Security Extensions",
RFC 4035, March 2005.
[9] Baker, F. and P. Savola, "Ingress Filtering for Multihomed
Networks", BCP 84, RFC 3704, March 2004.
Author's Address
Kurt Erik Lindqvist
Netnod Internet Exchange
Bellmansgatan 30
118 47 Stockholm
Sweden
Email: kurtis@kurtis.pp.se
URI: http://www.netnod.se/
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