Please select the answer that will allow you to success…

You are running a successful multitier web application on AWS and your marketing
department has asked you to add a reporting tier to the application. The reporting tier will
aggregate and publish status reports every 30 minutes from user-generated information that
is being stored in your web application s database. You are currently running a Multi-AZ RDS
MySQL instance for the database tier. You also have implemented Elasticache as a database
caching layer between the application tier and database tier. Please select the answer that
will allow you to successfully implement the reporting tier with as little impact as possible to
your database.

A.
Continually send transaction logs from your master database to an S3 bucket and generate the
reports off the S3 bucket using S3 byte range requests.

B.
Generate the reports by querying the synchronously replicated standby RDS MySQL instance
maintained through Multi-AZ.

C.
Launch a RDS Read Replica connected to your Multi AZ master database and generate reports
by querying the Read Replica.

D.
Generate the reports by querying the ElastiCache database caching tier.

Explanation:
Amazon RDS allows you to use read replicas with Multi-AZ deployments. In Multi-AZ
deployments for MySQL, Oracle, SQL Server, and PostgreSQL, the data in your primary DB
Instance is synchronously replicated to a standby instance in a different Availability Zone
(AZ). Because of their synchronous replication, Multi-AZ deployments for these engines offer
greater data durability benefits than do read replicas. (In all Amazon RDS for Aurora
deployments, your data is automatically replicated across 3 Availability Zones.)

You can use Multi-AZ deployments and read replicas in conjunction to enjoy the
complementary benefits of each. You can simply specify that a given Multi-AZ deployment is
the source DB Instance for your Read replicas. That way you gain both the data durability and
availability benefits of Multi AZ deployments and the read scaling benefits of read replicas.
Note that for Multi-AZ deployments, you have the option to create your read replica in an AZ
other than that of the primary and the standby for even more redundancy. You can identify the
AZ corresponding to your standby by looking at the “Secondary Zone” field of your DB
Instance in the AWS Management Console.