For the rate limiter design, I proposed a token bucket algorithm, which allows for bursts of requests while maintaining an average rate. I discussed the need for both local storage and distributed systems.

My explanation included the concepts of leaky buckets and how they apply to real-world scenarios, like regulating traffic flow. However, when I delved into implementation specifics, I realized I didn't cover edge cases like clock skew and distributed failure handling as thoroughly as I should have.

The interviewer appreciated my grasp of basic concepts but pressed me on scalability and fault tolerance, which caught me off guard. I managed to offer some ideas, but I felt there was a delay in my responses.