same $.ajax call is ASYNC in Chrome but SYNC in IE

Question

I have a dumb simple ajax call to a nonexistent url with an error callback:

$.ajax("non-nonexistent-url", {
    error: function () {
        alert("FOO");
    }
});
alert("BAR");

When I run it in Chrome, I get "BAR" then "FOO" alerts, which is the behavior I expect - ajax call is asynchronous. In IE, however, I get "FOO" then "BAR", which looks like synchronous call, but why? It should be async by default, right? I hoped it's guaranteed that $.ajax returns before any callbacks are executed...

Answer 1

An assumption on the reason :

If the host in the URL does not exist, no request is actually made. While in IE only the request is asynchronous, in other browsers the host lookup is also asynchronous.