Section 8: AWS Fundamentals: RDS + Aurora + ElastiCache

Question 1

What types of database engines are managed by AWS?

Answer 1

• Postgres
• MySQL
• MariaDB
• Oracle
• Microsoft SQL Server
• Aurora

Question 2

What is the max number of read replicas per a database instance?

Answer 2

15

Question 3

Read replicas can exist…

Answer 3

• Within AZ
• Cross AZ
• Cross Region

Question 4

Do read replicas within the same region (different AZ) get charged?

Answer 4

No. Same region replication is free.

Question 5

Does cross-region replication of Read Replicas get charged?

Answer 5

Yes, you need to pay a fee for cross-region replication.

Question 6

Can read replicas be set up as Multi-AZ (Disaster Recovery)?

Answer 6

Yes.

Question 7

What is the max number of replicas can Aurora have?

Answer 7

15 replicas

Question 8

What is at-rest encryption?

Answer 8

Data is encrypted in the volume.

Question 9

Can the replicas be encrypted if the master database is un-encrypted?

Answer 9

No, the master database must be encrypted.

Question 10

Is it possible to encrypt an un-encrypted database?

Answer 10

Yes, create a database snapshot, and restore the database as encrypted.

Question 11

How are RDS Proxy helpful?

Answer 11

• Minimizes and pool connections on the RDS database instance.
• Minimizes fail over time
• Enforces IAM authentication
• Stores credentials in the Secrets Manager Service

Question 12

What is the port number for Aurora?

Answer 12

3306

Question 13

What is cache churn?

Answer 13

It is when a lot of data needs to be written to the database and to the cache that will never be read. Which can be a problem if the cache is small.