Server request response time

I was asked this question during an interview and was not sure how to respond as I’m unfamiliar with web development:

You have a web application making requests to a server, and a server returnIng responses. The total time this takes is request time - response time or, x. Find all the previous request - response times that’re less than the current x (i.e., that were faster).

Any insight or similar problems would be interesting to see!