Your question is System Scalability Basics. 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).
What is Scalability? What is the difference between horizontal and vertical scalability?
Asked in the Technical+HR stage. Explain the concepts clearly and relate them to an end-to-end ML system where appropriate. Cover how you would choose between the two approaches, their tradeoffs, and relevant operational concerns.