Fun With RFC2606 DNS Names

[RFC 2606]( reserves several domain names that are safe to be used in documentation and testing. The idea is to avoid confusion and conflict when someone need to use domain names as example in documentation. For example: one might be tempted to use or as example in documentation. But these domains are owned and someone might use those examples in verbatim without realizing that these domains are owned by somebody else.

The reserved domain names are:

* .test (for testing)
* .example (for documentation and examples)
* .invalid (for domains that are sure to be invalid in examples)
* .localhost (for loopback address)

.test, .example and .invalid all don’t have records in the Internet name servers. .localhost does have an A record pointing to loopback address, and all point to and When someone types to their web browser, it will display the message:

> You have reached this web page by typing “”, “”, or “” into your web browser.
> These domain names are reserved for use in documentation and are not available for registration. See RFC 2606, Section 3.

These addresses have their SMTP port filtered, probably to avoid getting unintended emails :).

According to [Google](, there are about 2010 pages pointing to, and But Google probably treats them as a single site. These sites has pagerank 7. Not bad for a web site that only contains only one simplistic web page.

What about ‘example’ domain for other non country TLDs?,,,,,, all are NXDOMAIN. returns two name servers, but both didn’t answer query for points to two name servers, but both didn’t return any records for has an A record but probably resulted from a wildcard address.


  1. I try to always use example.(com|org|net) for all examples in my articles, but sometimes I am worried with a condition: if I need two domains for example, it is not clear enough for common users (especially they who have no technical background) to distinguish between example.COM and example.NET. Seems two clear different domain name is in need.

  2. #2: According to RFC2606, the best way is to use .example TLD, such as foo.example or bar.example. But ‘example’ is unusually long for a TLD. In my opinion, using .dom TLD is better. While not futureproof, it is short and sweet, it is not being used now, it looks like a real TLD and it rhymes with .com :).

  3. jadi inget, dulu ketika .cat belom di-resmikan, aku sempat make domain itu untuk catalyst. tapi setelah domain .cat diresmikan (tahun lalu?), jadi kagak bisa make itu lagi.

    untung sekarang ada RFC tentang domain lokal.

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