Skip to main content

Circular dependencies, DNS and impediments to IPv6 adoption

It is sometimes said that ISPs do not offer IPv6 transport and equipment vendors offer just partial IPv6 support because there is no customer demand. The counter argument is often made that consumers can only buy what is on offer so people prefer to buy production quality services and equipment.

Unfortunately, even when production quality IPv6 transport and network infrastructure are available it is not always possible to deploy a completely IPv6 accessible network. One problem is the difficulties domain name registrants have when they ask their domain name registrar to include their IPv6 glue in the DNS. Not many domain name registrars support glue registration for IPv6 addresses. This limits their ability to provide an IPv6 DNS service.

The problem was discussed during Registries and Registrars’ IPv6 workshop on the last day of the ICANN meeting in Paris. Raúl Echeberría explained the problems that LACNIC has experienced in registering the glue they need for

Mohsen Souissi of AFNIC then explained that IPv6 support in domain name registries is no longer the hard work it once was. Most of the tools that are needed already support IPv6 very well and have done so for some time. He was followed by Jean-Claude Michot of BookMyName who explained that introducing support for IPv6 glue was not a complicated process and was done very quickly.

It is possible for a registrar to provide support for IPv6 glue registration without running IPv6 on their network at all and deploying an IPv6 network is now far less painful than it once was. Michele Neylon from Blacknight described a generally positive experience.

We hope that more domain registrars will start offering IPv6 glue registration, which will make it easier for domain name registrants to go ahead and deploy their own IPv6 networks.


    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."