Message from Vint Cerf and
Stuart Lynn to Names Council
20 September 2002
Dear Names Council:
Over the past few weeks, questions have arisen regarding the IANA practice of obtaining and reviewing TLD zone files at the time of changes in the nameservers listed for the TLD in the root zone. The various points of view expressed suggest to us that it would be productive to re-examine the objectives for this practice and to consider alternative means by which those objectives might be reached. The principal motivation for this practice has been to improve the quality of the DNS service by validating the format of the TLD zone files to ensure correct configuration.
Considering that this examination has until now tended to be done by the IANA only when a TLD nameserver is being transferred to a new operating site, we believe it is appropriate to ask the Committee on Security and Stability (SAC) to look into the matter and to develop a longer-term recommendation as to what would be the most sound technical practices to follow to promote better DNS stability; and to provide an interim recommendation while the broader issues are being explored. Since this, however, involves domain names, we would want to enquire whether the DNSO concurs with this approach before asking the SAC to undertake this analysis.
Historically, the goal of the practice has been to improve the quality of data in the DNS. Pursuing the RFC 1591 policy that the IANA should make checks to verify nameserver "operational status and database accuracy", the IANA follows the practice of obtaining and technically reviewing TLD zone files as part of the technical checks it performs when nameserver changes are requested. Although checks for the most severe database misconfigurations can be performed by other means, many less severe errors have been detected through this review. The ordinary result of finding one or more of these less severe errors is to proceed with the root-zone change, to alert the ccTLD manager of the error, and to request that it be remedied.
DNS data accuracy continues to be an important, and by some measures increasingly urgent, goal. Recent "Domain Health" surveys conducted by Men & Mice <http://menandmice.com/6000/6350_eu_survey.html> and <http://menandmice.com/6000/61_recent_survey.html> have reported surprisingly high performance error rates in reviews of subdomains within various TLDs. While DNS quality at the TLD level appears to be much better, discussions at the November 2001 ICANN security meeting and the Domain Health surveys have demonstrated that it is important that the community work continuously to maintain and improve DNS quality. Particularly with increasing requirements from the broader society for security and trustworthiness within the DNS, it is important for the ICANN community to develop and implement practices that promote high-quality DNS data at all levels, and with a higher frequency than only at times when nameserver changes are contemplated.
Although with cooperation from the TLD managers (which has historically been quite high) the current IANA practice has served to locate and allow correction of many DNS errors, recently four TLD managers have denied the IANA download access to the zone files for their TLDs. Without having the zone files, there is no reasonably practical method for a third party to perform some checks of database accuracy. This disagreement has resulted in an unfortunate standoff situation that, perversely, frustrates attempts to locate and correct TLD configuration errors, and at the same time potentially introduces additional DNS data errors through configuration mismatches between the DNS data in the root zone (which remains unchanged) and the affected TLD zones (assuming the TLD manager proceeds to change the TLD zone).
This debate has prompted some very helpful initial ideas from the community regarding possible changes in practices that might be better suited to achieve the goal of improved DNS data accuracy. As pointed out by Thomas Roessler <http://www.dnso.org/clubpublic/ga/Arc11/msg00206.html>, the current timing of technical checks may not be optimally suited to the goal of improving DNS data quality. As one of us (Stuart) has pointed out, a strong argument can be made that TLD integrity checks would be more effective, and the process for making root-zone updates streamlined, by developing a possibly distributed and delegated process for performing TLD zone-file reviews on a periodic basis rather than as part of technical checks performed at the time of nameserver changes. <http://www.dnso.org/clubpublic/ga/Arc11/msg00210.html>
It appears to us that the issues about what practices should be followed by the IANA, TLD managers, and other participants in the ICANN process to promote improved DNS data quality is one that is ripe for examination. We believe that technical focus of these issues makes it appropriate to have at least the initial examination and analysis conducted by the ICANN Security and Stability Advisory Committee.
Because the issues also concern domain names (the focus of the DNSO), however, we would like feedback about whether the Names Council believes for any reason that it is inappropriate that they be referred to the Security and Stability Advisory Committee. Because an early resolution of these issues would be helpful to all concerned, we would appreciate your considering the appropriateness of the referral at your earliest convenience.
Our mutual interest is to take the opportunity occasioned by these discussions to encourage the development of more effective methods for improving DNS data quality at all levels in the system.
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