Ask HN: Technical interview questions that "walk the whole stack"?

For example, think questions like "What happens when you type an address in your browser and hit enter?" Questions which one could answer by going at great lengths and demonstrate the familiarity with the whole stack (networks in this case)?

It doesn't need to be about computer networks -- other fields like computer organization, operating systems, distributed systems, compilers & interpreters, computer security, algorithms & data structures, and so on.