The answer is not, "um, it depends on X", which usually indicate a lack of understanding of the problem as well as a lack of knowledge about the solution. People, especially tech nerds which tend to have ego issues, need to learn to just say "I don't know", or to simply not answer a question that they don't know the answer to. It doesn't depend on anything.

Preach!

Boy do they go red when you simply say "If you don't know the answer, please don't confuse people more."