Sharepoint 2010 is changing my internet hyperlink column url to my intranet url, why?

I have a content type with a hyperlink column.

If I create a page based on that content type and point the hyperlink field to a document in a li开发者_如何学Cbrary on our public url (eg: http://internet.test.com/documents/test.pdf) the url gets changed to point to the intranet/administration site (eg: http://**edit**.test.com/documents/test.pdf) which then fires the windows login prompt.

Why is Sharepoint changing the url of the item and how do I make it stay as http://internet.test.com/documents/test.pdf so anyone can download it.

Some people have mentioned Alternate Access Mapping, but I'm not sure how to implement it. Any help?

Those people are probably right. There's an interesting video on this site:

http://technet.microsoft.com/en-us/sharepoint/ff679917.aspx