Top level domain detection across nested iframes and different domains via javascript?

Question

I know about iframes from different domains unable to access pretty much anything on the parent level, BUT, all I would need to know is the top-most domain. Here is the scenario:

ABC.com loads an iframe from DEF.com that loads an iframe from XYZ.com. On the level of XYZ.com I need to know that ABC.com is the top most domain.

Any thoughts? Assuming top and intermediaries cooperation or without cooperation, are there any hacks for different browsers or?

I have been able to come up with several different ways to do this kind of thing on Firefox, but I'd be interested to see this exploited for IE in some way.

Answer 1

I can't remember if the same-origin-policy prevents reading of the location or not (obviously, writing or modifiction is out). But you can test it very easily.

From a page on XYZ.com

alert( top.location.href );

Answer 2

Peter is right.. just one little change, since u want the domain not the full url top.location.host - gives the port with the name or top.location.hotname - just domain name