Welcome to your interview.
The question is on your right: Scalable In-Memory Cache Design. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
Design a scalable in-memory caching system, detailing the classes, eviction policies, and thread-safety mechanisms.