How do you not know what DSL is?

Answer 1

I'm not certain how to answer the question (or why you're asking it), because I do know what DSL is.If you mean "how could a person chosen at random not know what DSL is" ... DSL is not important to most people in the world, so it's hardly surprising they'd have at best a vague idea of what it is.

DSL is only useful to people who live a) close (in a network topology sense) to a central office and b) want a high-speed internet connection in both directions. Since most people are far more interested in download speed than upload speed, cable is likely to be at least as fast as DSL for the purposes they care about, and probably cheaper.