In cs.stackexchange, we usually come across questions that have external links in them. For example, the question in Spanning tree display conventions points to a pdf document; without that document, the question does not make any sense.
A lot of times, these links point to documents that are uploaded outside stackexchange web site, e.g. course homepages. So, the links may change or be removed eventually. Thus, many questions would not make any sense after some time.
What should we do about this, as it might be a problem in near future. I am not sure whether we should ask that person to put enough information in the question body or we should just leave that question?