Skip to main content

Publication of TNO Report Describing Root Scaling Model

ICANN has published a report prepared by TNO entitled "Root Scaling Study: Description of the DNS Root Scaling Model" [PDF, 677K]. TNO (Netherlands Organization for Applied Scientific Research) is an independent research organization based in Delft, Netherlands ( This report is an additional product of the root scaling study led by Lyman Chapin of Interisle Consulting, and complements the "Scaling the Root" report [PDF, 1,340K] published on 18 September 2009. The TNO report describes the characteristics of a quantitative model developed by TNO for dynamic analysis of root scaling issues. The TNO model and simulation system are undergoing verification.

ICANN is soliciting public comment on both reports at The Root Scaling Steering Group is evaluating these reports and plans to provide an evaluation and recommendations for the Board and the public.

More Announcements
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."