DOP-C02 practice question: Multi-AZ and multi-Region high availability (2 of 3)

Resilient Cloud Solutions A free question from our original DOP-C02 practice exam. Try it, then open the answer to see why each option is right or wrong.

A hospital runs its patient-record reporting database on Amazon RDS for PostgreSQL in one Region, with the application servers in the same VPC. The database currently has a single instance in one Availability Zone.

If the Availability Zone fails, the hospital needs the database to fail over automatically within minutes, with no loss of committed transactions. The clinical applications connect with the database's existing endpoint, and the team cannot change their connection strings.

The hospital does not need cross-Region recovery for this database, and it wants the lowest operational effort.

Which change meets these requirements?

Choose one answer.

A. Convert the instance to a Multi-AZ DB instance deployment, with a synchronous standby in another Availability Zone and automatic failover under the same endpoint.
B. Create a read replica in another Availability Zone, and have the team change the connection string to the replica's endpoint whenever the primary becomes unavailable.
C. Create a cross-Region read replica in another Region, and promote it manually after an Availability Zone failure so that the application gets a new database endpoint.
D. Take a snapshot every hour, and restore a new instance from the most recent snapshot in another Availability Zone after a failure, then update the application connection strings.

Show the answer and explanation

Answer: A

A. Right: Correct. A Multi-AZ DB instance deployment replicates synchronously to a standby in a second Availability Zone, and RDS fails over automatically while the DNS endpoint stays the same. No connection string changes are needed. Learn more: Configuring and managing a Multi-AZ deployment for Amazon RDS (opens in a new tab)
B. Wrong: Read replicas use asynchronous replication, so committed transactions can be lost at failover. Changing connection strings during an incident also breaks the no-change requirement. Learn more: Working with DB instance read replicas (opens in a new tab)
C. Wrong: This adds cross-Region recovery the hospital does not need, and it is a manual process with a new endpoint. It also replicates asynchronously, which can lose recent transactions. Learn more: Working with DB instance read replicas (opens in a new tab)
D. Wrong: Restoring from a snapshot takes a long time and loses everything since the last snapshot. It also requires connection string changes, which the team cannot make. Learn more: What is AWS Backup? (opens in a new tab)

Explanation

A Multi-AZ DB instance deployment uses a synchronous standby in another Availability Zone and fails over automatically under the same endpoint, so the hospital needs no application changes. Read replicas, cross-Region replicas and snapshot restores each require endpoint changes or manual work, and asynchronous copies can lose recent transactions.

DOP-C02 practice question: Multi-AZ and multi-Region high availability (2 of 3)

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