What does stateless design mean for a service in terms of scalability?

• A. Stateless design means servers do not retain client state between requests, enabling scalability.
• B. Stateless design requires storing session data on each server.
• C. Stateless means the service cannot perform any computation.
• D. Stateless only applies to client-side applications.

Answer: (A)

Stateless design means the server does not keep any client-specific information between requests. Each request contains all the data needed to handle it, so any server can process it without relying on previous interactions. This makes horizontal scaling practical: you can add more servers behind a load balancer and route requests to any instance without worrying about sticking a user to a particular server. It also reduces the need to synchronize session data across servers, since that data can be kept elsewhere (or carried in the request).

The best answer reflects this idea: servers don’t retain client state between requests, enabling scalability.

Storing session data on each server would introduce state, which Stateless design avoids. The notion that the service cannot perform any computation is incorrect—statelessness is about state retention, not computational capability. And stateless applies to server-side services as well as client-side ones, so it isn’t limited to client-side applications.