Your question is Scalable Camera Health Dashboard. 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).
You have million+ camera which keep sending health signal to server. Goal is to design scalable system to show total number of healthy camera. Assume that camera emits event every 10 sec and we need to show latest count correctly within last one minute interval.
Asked in the phone screen stage. System design after coding.
Address the ingestion protocol, partitioning, stateful aggregation, storage, query serving, correctness under retries and out-of-order events, and monitoring. Discuss whether ML is necessary for the core count and where anomaly detection could add value.