First, a recruiter asks some behavioral questions, such as "Why Yelp?" and "What are the three things you care most about when choosing a job?" She also asked several one-sentence technical questions, which can all be found in the reviews.

This was followed by two phone interviews with engineers.

A load balancer question was posed: Given [(a, 1), (b, 1), (c, 8)], where a, b, and c represent machines, and 1, 1, and 8 represent their respective probabilities (e.g., 1/(1+1+8) chance of returning 'a', 8/(1+1+8) chance of returning 'c'), write code to implement the balancer. How would you test it?

Ask a lot about how you would test it.