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?

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

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