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Quiz: Design a Chat App

5 questionsNo time limitPass: 60%+10 XP on first pass

Design real-time messaging step by step: requirements, scale estimates, WebSockets, message flow, storage, online presence, delivery receipts, group chats and offline push.

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  1. Question 1

    Which technology lets the server push new messages to the phone instantly over one persistent connection?

  2. Question 2

    50 million users each sending 40 messages a day is how many messages per day?

  3. Question 3

    How should a chat system deliver a message when the receiver is offline?

  4. Question 4

    Where should photos and videos shared in chats be stored?

  5. Question 5

    How do chat apps avoid showing a resent message twice?