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Root Stability Study Draft Report Available for Public Comment

LOS ANGELES – 27 October 2016 – The Internet Corporation for Assigned Names and Numbers (ICANN) today published [PDF, 2.74 MB] a draft report regarding the Continuous Data-Driven Analysis of Root Server System Stability (CDAR). The study examines the technical impact of the New gTLD Program on the security and stability of the root Domain Name System (DNS).

Comment on the study.

ICANN commissioned the CDAR study, which was conducted by independent research organization TNO and its consortium partners, SIDN and NLnet Labs. The findings will help the ICANN community determine if additional steps are required to safeguard the root zone’s security and stability as more new gTLDs are delegated in the future. The ICANN Board of Directors adopted Governmental Advisory Committee (GAC) recommendation to:

  • Study the effects of the New gTLD Program on the operations of the DNS root system.
  • Postpone delegation of new gTLDs until it can be determined that the delegations in the current round have not jeopardized the root system's security or stability.

Key Findings and Recommendations:

The study did not find any evidence that the delegation of new gTLDs degraded the security and stability of the root DNS system. In the New gTLD Program, the rate of delegation has been kept at a gradual rate to ensure that timely mitigation actions can be taken in case signs of degradation are observed. The study’s authors advise that the rate of new gTLD delegations remain gradual.

They also recommended continuous monitoring of a set of risk parameters, most importantly the volume of DNS queries across all root servers, and the increase in the amount of processing required of root name servers, which would reduce traffic handling capacity of the servers.

Representatives from the CDAR research consortium will discuss the reported findings and solicit feedback during a session at ICANN57.

New gTLD Program Reviews

The CDAR study is part of a series of reviews assessing whether the objectives of the New gTLD Program are being met. The reviews are exploring a number of areas including the effects of the Program on competition, consumer trust and consumer choice; the effectiveness of the application and evaluation process, as well as the effectiveness of Rights Protection Mechanisms (RPMs) and other safeguards built in to the Program.


ICANN's mission is to help ensure a stable, secure and unified global Internet. To reach another person on the Internet, you have to type an address into your computer - a name or a number. That address has to be unique so computers know where to find each other. ICANN helps coordinate and support these unique identifiers across the world. ICANN was formed in 1998 as a not-for-profit public-benefit corporation and a community with participants from all over the world. ICANN and its community help keep the Internet secure, stable and interoperable. It also promotes competition and develops policy for the top-level of the Internet's naming system and facilitates the use of other unique Internet identifiers. For more information please visit:

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Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as"""" is not an IDN."