Your question is Tiered Security and Real-Time Feedback. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Describe various security considerations, protocols, and best practices applicable at each individual tier of a typical 3-tier web application, and explain how you would implement real-time like or dislike feedback for a news feed.