does AJAX use XML parser? if yes where it uses it? I think the java-script engine on the client side use the DOM parser to retrieve the required information from the received XML document which is received from the server. Am I right or AJAX does not use XML parser at all!
Ajax means asynchronous javascript and XML. http://www.w3schools.com/ajax/ajax_intro.asp
I guess you know it is used to calling server outside normal request. What does that mean? Server response only to GET and POST requests, so if you need load additional data after page was loaded, let's say load XML file you call server and server will send you those data (received data from server will be in text format JSON, XML whatever you code them on server side).
That part was to clarify you understand basics of AJAX, now to answer your question. In the previous link you have really nice example in which part Ajax uses XML files. In following link you can see processing of XML file received from server a http://www.w3schools.com/ajax/ajax_xmlfile.asp
I hope this answers your question.