Overview of internationalized domain names (IDN)

An internationalized domain name (IDN) is a domain name that contains non-ASCII characters - characters that are native to a region or language and do not belong to the ASCII standard, for example: http://www.färgbolaget.nu.

A typical domain name uses characters from the ASCII character set, for example, http://www.example.com. The network protocols, especially DNS, recognize only ASCII characters in a domain name. Non-ASCII characters therefore cannot be used in domain names without a mechanism to map these non-ASCII characters to their ASCII-encoded representations.

# How does IDN work?

Typically, when you use the browser to connect to a domain (comprising ASCII characters), the browser sends a request to the authoritative domain name server for the IP address corresponding to the requested domain. The DNS protocol requires the domain names to be represented using the ASCII character set.

In the case of IDNs, if a browser needs to resolve an internationalized domain name, it must first convert the domain name from its native character set to an alternative representation in the ASCII character set. This conversion is defined by a well-defined standard known as ASCII-compatible encoding (ACE) described in RFC 3490. When your browser automatically performs the translation for a domain name from its IDN representation to its equivalent ACE representation, it is said to be IDN-compliant.

Some of the IDN-compliant browsers are:

- Netscape Navigator 7.1 (or higher)

- Mozilla 1.4 (or higher)

- Microsoft® Internet Explorer

- Important: Microsoft® Internet Explorer requires the i-Nav plug-in from Verisign® to work correctly with IDN.

## Translation of IDNs to ASCII-compatible encoding (ACE) or Punycode

When an IDN-compliant browser receives a request for an IDN, it translates the domain name into a sequence of ASCII characters prefixed by xn--. The translated domain name is called ASCII-compatible encoding (ACE) or Punycode and complies with the network protocol standard.

For example, when you type http://www.färgbolaget.nu into a browser, the browser sends the following ASCII-encoded string to the DNS: http://www.xn--frgbolaget-q5a.nu

# Domain name representation in the control panel

The control panel displays the IDN representation of the domain name. To view its ASCII-encoded equivalent, click the link show text name next to the IDN. A pop-up window opens displaying the ASCII-encoded representation. The visual mapping enables you to easily co-relate an IDN with its ASCII-encoded representation.

# Caveats

IDN is based on evolving standards. As of now, not all browsers have in-built support for internationalized domain names. Therefore, you need IDN-compliant applications to take advantage of IDN.

Please review the following related topics for more information:

- IDN compatibility requirements for applications

- Using IDNs with email addresses

- Using remote access services to connect to IDN domains