Internationalized Domain Names (IDN)

Ramón Saquete

Written by Ramón Saquete

Internationalized domain names are created to be able to contain characters outside the ASCII standard, such as accents, umlauts, the eñe or Russian, Chinese, Japanese or Arabic characters.

The Domain Name System (DNS) standard only allows ASCII characters. It would be costly and problematic to change the standard worldwide, so without changing the DNS standard, the only way to solve the problem is to ASCII encode domain names with other characters.

This is done by means of the IDNA ToASCII algorithm using Punycode (RFC 3492).

Examples of IDNA coding:

  • The encoded domain “españ” is “”.
  • Japanese domain “読ませ大賞.jp” encoded is “”
  • The standard was implemented in 1998 for IDN gTLDs and in 2010 it was extended to IDN ccTLDs, which are those internationalized domains that allow country extensions such as “.es”.

Importance in SEO

In the past, domain names with keywords in the name had an impact on SEO, but this relevance factor has lost weight in the algorithm. However, it can generate more confidence in the user if the domain is in their language, so before choosing whether to use an IDN domain or not, we must assess what is our target audience.

IDN attacks with homographs

Homograph attacks consist of registering IDN domains of existing entities, replacing some ASCII character with a different character that is visually the same or similar, for example the Latin “a” and the “а” of the Russian Cyrillic alphabet. In this way, phishing attacks and other types of frauds are carried out, where the domain name appears legitimate.

Browsers try to solve the problem by displaying the encoded domain, instead of the text in its corresponding language, when characters from different alphabets are mixed.

Additional references

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Ramón Saquete
Ramón Saquete
Web developer and technical SEO consultant at Human Level. Graduated in Computer Engineering and Technical Engineering in Computer Systems. He is also a Technician in Computer Applications Development and later obtained the Pedagogical Aptitude Certification. Expert in WPO and indexability.