Design Zillow.

A robust Zillow design would likely employ a multi-layered sharding strategy. A primary shard key could be based on the real estate company listing the properties, as this provides a natural grouping for data management and access. This could then be further sharded by zip code to distribute data more granularly and improve query performance for location-based searches. This approach balances the need to handle properties spanning multiple zip codes with efficient retrieval of listings within specific geographic areas.