I was asked this question once at an interview:
"Suppose you own a website where the server is at some remote location. One day, some user calls/emails you saying the site is abominably slow. How would you identify why the site is slow? Also, when you check the website yourself as any user would (using your browser), the site behaves just fine."
I could think of only one thing (which was shot down):
I was kind of lost because I had never thought of this problem. I have almost no idea how running a server/website works. So if someone could highlight a few approaches, it would be nice.