A large size Aurora replica is added to the existing single-master Aurora DB cluster. This cluster already consists of a primary DB instance & four Aurora Replicas. All the existing Read replicas have priority settings as tier-4. A newly created Aurora replica should not be promoted as a primary instance in case of failure of the primary instance.
What setting can be done on the new Aurora Replica to meet the requirement?

Answer options:

A.Configure priority as tier-15 for the new Aurora Replica.
B.Configure priority as tier-0 for the new Aurora Replica.
C.Configure priority same as another Aurora Replica for the new Aurora Replica.
D.Configure priority as default for the new Aurora Replica.

Correct Answer: A
Aurora Replicas serves two purposes,
To scale read operations for the application.
To promote as a Primary Instance, in case of failure in the primary instance.
In case of multiple Aurora Replicas, priority value can be used to control the order in which a Replica can be promoted as a primary instance. Valid Range is from 0 to 15, with 0 as the highest priority. If no priority values are set, it is assigned a default value as 1. In the above scenario, to make sure a new Replica is not promoted as a Primary instance, a lesser priority (higher number) than the existing priority value of 4 should be assigned to the new replica.
Option B is incorrect as Configuring priority as tier-0 will make it first preference to be promoted as Primary instance post failure in Primary instance.
Option C is incorrect as when the priority value is the same for two or more Aurora Replica, Replica with larger size is promoted as a primary instance.
Option D is incorrect as when priority is set as default, it selects value as tier-1. This will make new replicas a higher priority to be promoted as primary instances.
For more information on setting priority values for replicas in Amazon Aurora, refer to the following URLs,
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-replicas-adding.html
https://aws.amazon.com/blogs/aws/additional-failover-control-for-amazon-aurora/