As i did not know exactly about how hashtag works hence asked about what exactly we are looking to design. Asked the functional requirements but he was not interested to give the requirement and he even was not interested in design diagram or how component interacts. 2 . I asked about the capacity/DAU he was not interested to answer. My answer : Twitter ashtag Function requirement: 1 . User can see top(10) trending hashtag 2 . Will vary trending hashtag user? 3 . Periodically, it will be shown different Capacity: Need to think on twitter level scale Hashtag table: Acko Bangalore User table User-1 user-2 HashtagUser User-1 acko User-2 bangalore Component: 1 . Aggregator service: Collect all the top trending data from hashtaguser table 2 . Caching (top 10 trending hashtag) Acko : 100 Bangalore : 80