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CDAR Study Cannot Predict Stability of the Root Server System

  • To: comments-cdar-study-plan-02dec15@xxxxxxxxx
  • Subject: CDAR Study Cannot Predict Stability of the Root Server System
  • From: Daniel Karrenberg <daniel.karrenberg@xxxxxxxx>
  • Date: Tue, 26 Jan 2016 12:42:55 +0100

Hash: SHA256

To whom it may concern,

Research is most useful and should be called scientific research only
when it can be verified and possibly reproduced by other researchers
and scientists.  Therefore we support the researchers' intention to
base their study on openly available measurement data and meta-data
wherever possible.  Where this is not feasible the observations and
meta-data should at least be available to other researchers under
reasonable conditions.

The DNS root name server system is a complex system with hundreds of
servers, tens of thousands of clients and millions of users all
connected by the open Internet and subject to unpredictable use and
abuse.  The proposed core methodology of the study is a "quantitative
model" based on measurement of past behavior of the DNS root server
system.  Models of complex systems are by their nature
simplifications.  Well constructed models may indeed be very useful to
predict possible instabilities in the real-world systems. However
these models cannot predict the *absence* of instabilities in complex
real-world system with any useful level of confidence.  In other
contexts this is referred to as "past performance is not necessarily
indicative of future results".

Our main comment and advice to the researchers is to carefully avoid any
perception that their results predict the absence of instabilities in
the DNS root name server system unless the results solidly support
such claims.

Our main comment and advice to ICANN is: do not expect the study to
predict the absence of instabilities in the DNS root name server
system including absence of instabilities that may be wholly or partly
caused by root zone expansion. ICANN therefore must make proper
contingency plans for the unpredictable cases where root zone
expansion causes or contributes to instabilities in the DNS root sever

Daniel Karrenberg
Chief Scientist
RIPE NCC, not speaking on behalf of the RIPE NCC

- ----
Some relevant experience: 30+ years of operational experience in DNS;
15+ years of operational experience and responsibility for
k.root-servers.net; contributor to DNS software diversity by instigating
and helping with design and implementation of NSD 1.0, an authoritative
name server; inventor and principal implementor of 'dnsmon', the first
comprehensive and public monitoring system for high level DNS servers;
co-inventor and responsible for the initial deployment of RIPE Atlas,
the active measurement system proposed to be used in the study.

ICANN entanglements: member of ICANN RSSAC since its inception and not
speaking on behalf of RSSAC either.


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