Real-Time Systems Interview Questions

Real-time systems maintain a persistent connection so the server can push rather than wait to be polled. That single change — from stateless requests to long-lived connections — is what makes these designs distinctive: connections are state, state has to live somewhere, and load balancing something stateful is harder than load balancing something stateless.

What interviewers probe

Interviewers probe connection state first: which server holds a given user's socket, what happens when that server restarts, and how a message reaches a user connected elsewhere. Presence is a favourite follow-up because it is deceptively expensive at scale. For collaborative editing, the expected discussion is conflict resolution and why last-write-wins is inadequate when two people edit the same region.