Silverlight: When do Xap files get downloaded and when are they cached?

A friend recently asked me “When do [silverlight] xap files get downloaded and when are they cached [in the browser]?”

So, using fiddler, I set out to find that answer:

Here are my test results.

To prepare, I deleted my temporary internet files and closed my IE window so there is no iexplore process running on my computer.

1. I load a new IE window - xap is loaded from cache
1. which I found odd because I thought deleting the files would have wiped my temporary internet files
2. I refresh the page (F5) - xap is loaded from cache
3. I force refresh the page (Ctrl+F5) - xap is loaded from cache
4. I do a clean and rebuild my solution, making a new xap file
5. I refresh the page (F5) - xap is loaded from cache
6. I force refresh the page (Ctrl+F5) - xap is loaded from cache
7. I close my IE window so there is no iexplore process running on my computer
8. I load a new IE window - new xap is download from server
9. I refresh the page (F5) - xap is loaded from cache
10. I force refresh the page (Ctrl+F5) - xap is loaded from cache
11. I close my IE window so there is no iexplore process running on my computer
12. I load a new IE window - xap is loaded from cache

Therefore, my testing shows a new xap is downloaded next time IE is restarted on the client.

Hope that helps someone.