Question

Difficulty: MediumDatabase High Availability

A company runs a production application using an Amazon RDS for MariaDB DB instance configured in a Multi-AZ deployment. During a scheduled maintenance window, Amazon RDS performs a failover to the standby replica. The SysOps Administrator needs to confirm that the failover was successful and ensure that the application servers reconnect to the newly promoted primary instance as quickly as possible. Which of the following actions should the SysOps Administrator take? (Select TWO.)

  1. Monitor the Amazon RDS events for the DB instance to verify that a failover has started and completed.Answer
  2. Ensure that the DNS caching configuration (TTL) on the application servers is set to a low value so that they quickly resolve the DB instance CNAME record to the new primary IP address.Answer
  3. C
    Manually promote the standby read replica to primary using the Amazon RDS console to complete the failover process.
  4. D
    Modify the application configuration files to point to the dedicated DNS endpoint of the standby replica.
  5. E
    Configure an Amazon Route 53 failover routing policy to redirect database connections from the primary database IP address to the standby database IP address.

Answer

To verify the failover status and ensure rapid application reconnection, the administrator should monitor the Amazon RDS events and configure a low DNS caching TTL on the application servers.
The correct options recommend monitoring Amazon RDS events to verify failover completion and configuring client-side DNS TTL settings to a low value. Since Amazon RDS manages Multi-AZ failover by updating the CNAME record for the DB instance endpoint, the application needs to query DNS for the new IP address quickly without using cached values.

Step-by-Step Solution

1
Check the Amazon RDS events for the DB instance.
Locate events showing the failover started and completed.
Amazon RDS logs failover activities as service events, providing a definitive audit trail of the transition.
2
Analyze client-side DNS caching settings on application servers.
Set client or OS-level DNS TTL to a small value (e.g., less than 30 seconds).
Amazon RDS Multi-AZ failover relies on updating a CNAME record. If the client caches the old IP address, it will continue attempting to connect to the offline primary instance.

Key Concept

Amazon RDS Multi-AZ failover utilizes automatic CNAME redirection, requiring short client-side DNS caching (TTL) for quick application recovery.
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