Strong consistency guarantees what in a distributed system?

• A. Reads reflect the most recent write across all nodes.
• B. Reads may return stale data.
• C. Writes may fail.
• D. System becomes partitioned.

Answer: (A)

Strong consistency means reads reflect the most recent write across all nodes, making the system appear as if there’s a single, global order of operations. To achieve this, replicas coordinate so that once a write is considered complete, all reads observe that latest value, regardless of which node is queried. This is why a read cannot show older data after a newer write has completed—a property often described by linearizability.

This differs from weaker models where reads can return stale data, and it’s not about writes failing or the system inevitably becoming partitioned; those can happen independent of the consistency level. Strong consistency focuses on what a read sees relative to the most recent write.