Effect Before Cause

A social feed replicates asynchronously across regions. Which anomalies does causal consistency rule out that plain eventual consistency permits? Select all that apply.

A client reads a newer value, then reads an older value from the same key moments later

Two replicas end up holding different values forever even though all writes have stopped

A reply becomes visible in a region before the post it replies to

A client's own just-acknowledged write is missing from that client's next read

Two unrelated writes made concurrently by different users are observed in opposite orders by two regions