|You haven't said whether you or he made a typo when you typed this:|
That won't work properly because of the incorrect / after www.
Depending on where you type it in what browser or what search engine box in the browser , you'll either get an error message like he got, or a list of suggested sites that may or may not have the actual site listed.
The correct au.yahoo.com will work with any browser or search engine.
Whether typing an incorrect address auto redirects you to the correct address, if it's a commonly mis-typed address, or you typed a legitimate older address for a site that is no longer used, depends on whether the particular browser or browser version or search engine or version of it has the info that tells it to re-direct to the correct address.
Typing www.yahoo.au will auto re-direct you to the correct au.yahoo.com address when you use some browers/browser versions/search engines, and won't with others. If it won't, sometimes you get a message like he got, sometimes you get a page that suggests "did you mean..." or similar and you can chose a suggested site, or the browser or search engine makes a guess and lists sites that may or may not be the one you were trying to access. .
In the case of my typing www.yahoo.ca and being auto re-directed to ca.yahoo com, the correct address was www.yahoo.ca for many years, then they changed it to ca.yahoo.com, and someone went to the trouble to make the auto re-direction to the correct address work in many browsers. It may have been the same situation for www.yahoo.au in the past, but someone enabled the auto re-direction for fewer browsers.
Which computer you type the address in makes no difference if everything else is the same - the result is the same. You and he both using Firefox doesn't necessarily mean you both have the same situation.
There are lots of variables.
Each browser has a default search engine version, and each version of a browser has a default search engine version.
E.g. is he using the same Firefox version as you are?
That browser's default search engine can be changed by you,
- by you deliberately manually changing settings in the browser settings yourself,
- or - automatically when you install an additional search engine, or by you installing software that includes installing an additional search engine by default and you didn't de-select that, which often by default may change the default browser search engine so that it uses the added search engine for the browser, unless you select otherwise.
I am working on a new Vista installation on a friend's computer that's been upgraded to include SP1 updates. I have installed IE 8 on it. The default search engine in IE 8 is Live search? Installing AVG 8 installs a Yahoo Search engine version in IE 8 by default, and installing something else installed a Google search version by default - I chose to NOT make the default search engine change to Yahoo or Google as suggested when asked after starting up IE 8 the first time after each of the Yahoo and Google search engines had been installed - if I had not done that, the default IE 8 search engine would be whatever I installed of those last, not the default one for IE 8.
In IE 8, you can find the search engine being used by default for IE in Tools - Internet Options - Programs. There's probably somewhere similar in Firefox.
In IE 8 on that Vista installation, there is the IE address bar at the top, a MSN/ Sympatico search box on the default home page, and a Google search box. I usually use Yahoo Canada - ca.yahoo.com - for searches using words. I often get different results depending on which place I type an address or search words in.