Your question is Distributed Write Safety. 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).
How would you ensure no two writes happen to a single resource in a distributed system (synchronized blocks / distributed locking)?
Asked in the Round 2 stage. Focus on how you would prevent concurrent writes across multiple app servers and what happens when a lock holder crashes or times out. Keep the answer practical and explain the tradeoffs of your approach.