Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework

Abstract

This document is one of a collection that, together, describe the protocol and usage context for a revision of Internationalized Domain Names for Applications (IDNA), superseding the earlier version.

Request Routing Redirection Interface for Content Delivery Network (CDN) Interconnection

“…This dns dictionary MUST contain the following keys: resolver-ip, qtype, qclass, and qname; the value of each MUST be the value of the appropriate part of the User Agent's DNS query/request. For internationalized domain names containing non-ASCII characters, the value of the qname field MUST be the ASCII-compatible encoded (ACE) representation (A-label) of the domain name [RFC5890].…”

The Network Access Identifier

“…The "utf8-realm" portion of the NAI is intended to be compatible with Internationalized Domain Names (IDNs) [RFC5890]. As defined above, the "utf8-realm" portion as transported within an 8-bit clean protocol such as RADIUS and EAP can contain any valid UTF-8 character.…”

“…It is instead an IDNA-valid label, as per the first item in Section 2.3.2.1 of [RFC5890]. As noted in that section, the term "IDNA-valid label" encompasses both "A-label" and "U-label".…”

DNS-Based Service Discovery

“…In addition, because Service Instance Names are not constrained by the limitations of host names, this document recommends that they be stored in the DNS, and communicated over the wire, encoded as straightforward canonical precomposed UTF-8 [RFC3629] "Net-Unicode" (Unicode Normalization Form C) [RFC5198] text. In cases where the DNS server returns a negative response for the name in question, client software MAY choose to retry the query using the "Punycode" algorithm [RFC3492] to convert the UTF-8 name to an IDNA "A-label" [RFC5890], beginning with the top-level label, then issuing the query repeatedly, with successively more labels translated to IDNA A-labels each time, and giving up if it has converted all labels to IDNA A-labels and the query still fails.…”