Technical and academic writers often need to use some domain name as an example to illustrate a concept or some technical issue. This site ("xx.co.za" or "www.xx.co.za") exists to be used for this purpose.
The need for domain names to be used for examples was realised years ago and RFC 2606 reserves the TLD "example" for this use. The same RFC reserves the TLDs "test", "invalid" and "localhost" for special use. More relevant for the current site, RFC 2606 notes that IANA has reserved the domains "example.com", "example.net" and "example.org" to be used for examples.
There are many reasons why one cannot use just any name as an example: Some names are trademarked and use of a domain name may infringe on the rights of its owners. In fact, often one needs to state that a site is "bad" in some sense or another. In a paper on digital forensics I, for example, wanted to say "suppose we know some site <site> contains pornography". Even though this example was for pure academic purposes, the owner of any domain I named for such an example would, in all likelihood, not have welcomed the example. While it is possible to use an unregistered domain for this purpose, the name may be registered in future - and one's use of the name may still lead to unhappiness (or worse). It is even possible that someone takes up the hint and registers it for the "bad" purpose it served as an example for - and one's academic or technical paper serves to direct some people to such unwanted content.
For many purposes when one wants to name an example, "example.com" works very well: It is immediately recognisable as an example and Internet authorities are unlikely to register it for any other use in future. A domain such as "host1.example" is also safe in the sense that it won't be used for other purposes in future; however, this domain name is perhaps less recognisable as a domain, since fewer people will recognise "example" as a TLD.
These "safe" examples do, however, have a few potential problems. The first problem is the relative length of these names. A URL such as "http://www.example.com" is 22 characters long; while this does not sound serious, such long "words" often cause line breaking problems when a paper's text has to be justified. The URL "http://www.example" is somewhat better, because it is only 18 characters long. However, as already noted, to many people this will not 'look' authentic. When one uses "http://www.xx.co.za" as an example, it occupies 19 characters. The three characters saved over "http://www.example.com" do not look like much, but will fit into some lines where the longer URL will not fit... (The shorter URL saves 13.636% over the longer one.) If one can omit the "www" from the example, the savings increase to 15.789% - again not that much, but often sufficient for one's needs. Even if the text does not have to be justified problems can occur: In my default screen resolution the URLs mentioned in this paragraph, in fact, do not break well.
If the reason given in the previous paragraph for wanting a different example site looks flimsy, it is because it probably is (for most cases). So let's consider the second reason for using "xx.co.za" as an example: Why can't I fulfil my patriotic duty of promoting my country, South Africa, by using examples that may make readers more aware of its existence (and its Internet presence)? (Let's ignore the fact that some of my examples will be bad ones, such as "cracker.xx.co.za"...) In fact, many people are unaware of the significant level of Internet activity in South Africa. As one indication of the level of activity, see the Internet Systems Consortium's biannual Internet Domain Survey. In January 2005, the "za" TLD was the 40th largest out of 258 TLDs.
It also seems that "xx.co.za" is already used as an example in a number of places - a search on Google identifies some of these cases. (When this site was launched on 16 June 2005, 38 matches - including some duplicates - were found by this search.) Formally registering "xx.co.za" for this purpose therefore supports this existing practice.
Anyone is free to refer to "xx.co.za" or "www.xx.co.za" for purposes of an example in academic and technical writing. This permission will persist for as long as I own the site. Who knows, I may even one day include links to such documents that use it as an example. However, the site is not intended for other purposes, such as software testing. RFC 2606 provides sufficient support for that. Personally I will also use the site for an academic experiment or two, on a page that is not intended for use by homo sapiens.