Amazon RDS MySQL DB instance with Multi-AZ functionality enabled to synchronously replicate the data Standby DB in Multi-AZ- synchronous replication Read Replica always asynchronous. so option C is ignored.

RDS Multi-AZ = Synchronous = Disaster Recovery (DR) Read Replica = Asynchronous = High Availability

Answer is B Find the below URL for the perfect explanation for the differences between: - Multi-AZ DB - Multi-Region DB - Read replicas DB https://aws.amazon.com/rds/features/read-replicas/

Multi AZ for availability

Option A is incorrect because Amazon RDS does not support synchronous replication to three nodes in three Availability Zones. Option C is incorrect because while you can create a read replica in a separate AWS Region1, the replication from the primary DB instance to the read replica is asynchronous, not synchronous.

B. Create an Amazon RDS MySQL DB instance with Multi-AZ functionality enabled to synchronously replicate the data. Enabling Multi-AZ functionality in Amazon RDS ensures synchronous replication of data to a standby replica in a different Availability Zone. This provides high availability and minimizes data loss in the event of a database outage. A. Creating an Amazon RDS DB instance with synchronous replication to three nodes in three Availability Zones would provide even higher availability but is not necessary for the stated requirements. C. Creating a read replica in a separate AWS Region would provide disaster recovery capabilities but does not ensure synchronous replication or meet the requirement of storing every transaction on at least two nodes. D. Using an EC2 instance with a MySQL engine and triggering an AWS Lambda function for replication introduces unnecessary complexity and is not the most suitable solution for ensuring reliable and synchronous replication.

B since all other answers r wrong

B Since read replica is async.

Multi AZ is not as protected as Multi-Region Read Replica.

I curios to know why A isn't right. Is it just that it would take more effort?

B is correct C requires more wokr.

Option B

Multi-AZ will give at least two nodes as required by the question. The answer is B. Amazon RDS provides high availability and failover support for DB instances using Multi-AZ deployments with a single standby DB instance. https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.MultiAZSingleStandby.html

Option B

Option A is the correct answer in this scenario because it meets the requirements specified in the question. It creates an Amazon RDS DB instance with synchronous replication to three nodes in three Availability Zones, which will provide high availability and durability for the database, ensuring that the data is stored on multiple nodes and automatically replicated across Availability Zones. Option B is not a correct answer because it creates an Amazon RDS MySQL DB instance with Multi-AZ functionality enabled, which only provides failover capabilities. It does not enable synchronous replication to multiple nodes, which is required in this scenario.

Maybe C since Amazon RDC now supports cross region read replica https://aws.amazon.com/about-aws/whats-new/2022/11/amazon-rds-sql-server-cross-region-read-replica/

B is correct