AWS Certified Solutions Architect Professional SAP-C02 Practice Question

Amazon ElastiCache for Redis with Global Datastore satisfies every stated requirement. A primary cluster in us-east-1 with a secondary cluster in eu-west-1 provides managed cross-Region replication that typically lags by less than one second, and promotion of a secondary cluster completes in under a minute. Redis keys allow native per-key TTL, so configuring a 1 800-second expiration automatically evicts session objects without additional code. ElastiCache is a fully managed service that handles patching, scaling, backups, and Multi-AZ failover, and it stores data only in memory, which matches the ephemerality requirement.

MemoryDB Multi-Region is incompatible because its current limitations block TTL/EXPIRE commands, so 30-minute key expiry cannot be enforced. DynamoDB global tables with DAX offer global replication, but DynamoDB's Time To Live deletes items on a best-effort basis that can take up to two days, meaning stale sessions could remain long after they should be removed. Aurora global database would replicate data but cannot deliver sub-millisecond cache-like latency and would require custom cleanup logic, increasing operational burden. Therefore, ElastiCache Global Datastore is the only option that fully meets latency, TTL, replication, and managed-service goals with minimal effort.