How would you answer an interview scenario involving availability and fault tolerance?

For an interview scenario involving availability and fault tolerance, I would first clarify the business goal, scale, constraints, and the failure or quality attribute the interviewer wants to explore. Availability is the proportion of time a service is usable, while fault tolerance is its ability to continue operating despite component failures. For production, define SLOs, remove critical single points, spread across failure domains, automate failover, and test failure behavior. I would then explain the main alternatives and tradeoffs, identify likely failure modes, and describe how I would validate the solution through testing, observability, security controls, and recovery or rollback planning.