Let assume, one question is about how to download a file directly and I've to add an valid link for example. Which link can I add in my answer so that no one can flags my answer as spam or copyright or something.
there's VERY few cases where you'd want to do that
The real issue is - how do you keep critical information to an answer (an artifact we hope should have an indefinate shelflife) available even after you can't maintain it.