Resource management techniques, such as cache optimization, are employed to organize resources within caches such that the most requested content (e.g., the most popular content) is more readily available. A service provider utilizes content expiration data as indicative of resource popularity. As resources are requested, the resources propagate through a cache server hierarchy associated with the service provider. More frequently requested resources are maintained at edge cache servers based on shorter expiration data that is reset with each repeated request. Less frequently requested resources are maintained at higher levels of a cache server hierarchy based on longer expiration data associated with cache servers higher on the hierarchy.