Can an IT system (client/server or web based) exist without a persistent data repository?

Can an IT system (client/server or web based) exist without a persistent data repository? If so how, and are there any caveats with this approach? If not why not- what are the reasons that make this difficult/impossible)?

Overview

Use the internet to research each exercise and provide answers to each exercise or parts of each exercise. In all cases, provide URLs as foundation for your findings (as for all internet references, provide the complete web page citation down to the individual page, not just the high level address – see the course FAQs under the course prefatory topics for an example). Please identify yourself in the body of any submission to me as this is the only way I can track input from over 40 students. The length guidance is the same as for the discussion question above, so remember to be concise, and summarize your ideas and reference sources – don’t just cut and paste a long section. Remember to reference your sources.

Use MS Word for the word processor. Always identify yourself in the body of your submission or attachment otherwise it is impossible for me to keep track of submissions for each student.