Which statement best describes eventual consistency?

• A. Reads always show the most recent write immediately.
• B. Reads may reflect stale data, and updates are never propagated.
• C. The system guarantees strict ordering of all operations.
• D. Updates propagate to all replicas eventually, allowing temporary inconsistency.

Answer: (D)

Eventual consistency describes a distributed replication model where updates are applied to replicas asynchronously. After a write completes, the new value is propagated to all replicas, but some reads may hit replicas that haven’t yet received the update, so you can see older data temporarily. Given enough time and no further conflicting writes, all replicas converge on the same value. This allows higher availability and fault tolerance, especially during network partitions. The statement that updates propagate to all replicas eventually, allowing temporary inconsistency, captures this behavior precisely. By contrast, insisting that reads always show the most recent write immediately would imply strong consistency; saying updates are never propagated is incorrect; insisting on strict ordering of all operations is even stronger than necessary and not what eventual consistency guarantees.