all browsers can support Ajax?

Answer 1

All latest version of all browsers support Ajax.

Answer 2

The answer is yes... and no!
They support AJAX if they support Javascript and XML.
However, they support it somehow differently, so you have to adapt your code.
Write your pages, then check them with IE7, FF, Netscape, Safari and Opera.
If it works fine with these, it "should" work fine with all others.
The biggest problem is the CACHE on the browser:
As the page is loaded, it is "cached" (saved on the user machine), so it can be re-displayed WITHOUT having to call the page again from the server.
Since AJAX is a "hidden" exchange between the server and the client, quite often, instead of updating the page, the bl**y thing reloads what you already have on your machine, defeating the purpose of AJAX!

Answer 3

Ajax is a language that combines Javascript and XML. So, if your browser doesn't support Javascript and/or XML then it does not support Ajax. Most modern browsers do support it however.