Kevin asks Wes to design Dropbox, with an emphasis on designing the data model and storage techniques to scale out.
Helpful links:
https://www.geeksforgeeks.org/design-dropbox-a-system-design-interview-question/
https://www.youtube.com/watch?v=PE4gwstWhmc
https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API
https://www.ibm.com/cloud/learn/object-storage