Amazon RDS read replicas provide scalability, flexibility and high availability for databases. Learn about manual promotion, cross-AZ and cross-region support, and access for read scaling.
Table of Contents
Question
Which of the following are characteristics of Amazon RDS read replicas? (Choose THREE.)
A. Can be manually promoted to a standalone database instance
B. Database engine version upgrades happen on primary
C. Can be within an Availability Zone, cross-Availability Zone, or cross-Region
D. All instances are accessible and can be used for read scalability
E. Synchronous block-level replication
F. Asynchronous storage capacity
Answer
A. Can be manually promoted to a standalone database instance
C. Can be within an Availability Zone, cross-Availability Zone, or cross-Region
D. All instances are accessible and can be used for read scalability
Explanation
Amazon RDS read replicas use asynchronous replication. All read replicas are accessible and can be used for read scaling. Read replicas can be within an Availability Zone, across Availability Zones, or across Regions. The database engine version upgrade is independent from the source instance. Read replicas can be manually promoted to a standalone database instance.
A. Read replicas can be manually promoted to become standalone database instances. This is useful if you need to make the read replica a primary instance, such as for disaster recovery or to scale write capacity. The promotion process breaks replication and converts the read replica into a fully writeable DB instance.
C. Read replicas can be created in the same Availability Zone as the primary instance for low-latency reads, in a different AZ in the same region for increased availability, or in a completely different AWS region for even better disaster recovery and locality to application servers. This flexibility allows optimizing for performance, availability and geographic distribution.
D. All read replica instances are fully accessible and can be directly queried by applications to scale read capacity and throughput. You can create one or more read replicas and distribute read traffic amongst them, while sending all writes to the primary instance which then replicates changes asynchronously to the read replicas.
The other options are incorrect:
B is wrong because database engine version upgrades happen independently on each read replica, not on the primary.
E is incorrect as replication to read replicas is asynchronous, not synchronous.
F is incorrect as read replicas use block-level asynchronous replication, not storage capacity.
In summary, the key characteristics of RDS read replicas are the ability to manually promote them to standalone instances, flexible AZ and cross-region deployment options, and direct accessibility for read scaling. Let me know if you have any other questions!
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