AWS Certified Solutions Architect Professional SAP-C02 Practice Question

The correct solution uses Amazon Aurora and Amazon ElastiCache for Redis, as this combination provides the highest level of managed high availability for both the database and caching tiers.

• Amazon Aurora PostgreSQL-Compatible Edition with a Multi-AZ cluster offers superior high availability and faster failover times (typically under 30 seconds) compared to standard RDS Multi-AZ. Its cloud-native, self-healing storage architecture, which replicates data six ways across three Availability Zones, is ideal for critical applications and minimizes operational overhead.
• Amazon ElastiCache for Redis with Multi-AZ automatic failover enabled meets the requirement for a highly available caching layer. If the primary cache node fails, ElastiCache automatically detects the failure and promotes an available read replica to become the new primary, ensuring minimal disruption.

Incorrect options are flawed for the following reasons:

• Using Amazon ElastiCache for Memcached is incorrect because it does not support native replication or automatic failover capabilities. Managing failover would require custom client-side logic, which increases operational complexity.
• Using an Amazon RDS read replica for high availability is incorrect. Read replicas are primarily for read scaling, and promoting one to a primary instance is a manual process that does not meet the automatic failover requirement.
• Using Amazon DynamoDB Accelerator (DAX) is incorrect as it is a purpose-built cache for Amazon DynamoDB, not a general-purpose cache suitable for a PostgreSQL database.
• Proposing a self-managed database cluster on EC2 directly contradicts the requirement to minimize operational overhead, as it would require significant effort to manage patching, backups, replication, and failover logic.