1. WebSockets & Realtime advanced

    2.4 million live WebSocket sessions sit on a gateway fleet being retired this quarter, with a replacement fleet ready in the same region. Sequence the cutover so no session is forced to reconnect more than once and the subscription path is never asked to absorb a storm.

    3 min answer websocketscutoverdrainingreconnect
  2. WebSockets & Realtime advanced

    A chat platform's websocket edge gateways lose a region to a cloud networking failure. How should reconnect storms, session resumption, message-gap recovery and gateway draining be designed so a 30-second outage does not become a 3-hour one?

    3 min answer slackwebsocketsreconnect-stormthundering-herd
  3. WebSockets & Realtime intermediate Multiple choice

    A collaborative editor needs to push document changes to connected clients with minimal latency. Which transport should it use, and what does the choice imply for infrastructure?

    2 min answer websocketssserealtimestateful-tier
  4. WebSockets & Realtime advanced

    A dashboard product uses WebSockets for live updates. It works at 5,000 concurrent users and falls apart at 50,000. Diagnose the architectural issues.

    2 min answer websocketsssebackplanefan-out
  5. WebSockets & Realtime advanced

    A deployment drops 200000 WebSocket connections at once. Describe what happens next and how you would make it safe.

    3 min answer websocketsreconnect-stormslackdeployment
  6. WebSockets & Realtime advanced

    A trading platform must push live prices to hundreds of thousands of concurrent connections. What are the architectural constraints of that fan-out, and how does it differ from the order path?

    2 min answer zerodhawebsocketsfanoutconflation