RDS + Aurora + ElastiCache

Question 1

What does RDS stand for?

Answer 1

Relational Database Service

Question 2

Which databases are supported by RDS?

Answer 2

Postgres, MySQL, MariaDB, Oracle, MS SQL Server, IBM DB2, Aurora

Question 3

What are advantages of RDS over EC2-deployed databases?

Answer 3

Managed service with provisioning, backups, scaling, monitoring, but no SSH access.

Question 4

What is RDS Storage Auto Scaling?

Answer 4

Automatically increases storage when free space drops below 10%.

Question 5

What is the difference between RDS Read Replicas and Multi-AZ?

Answer 5

Read Replicas improve read scalability; Multi-AZ improves disaster recovery.

Question 6

How many Read Replicas can RDS have?

Answer 6

Up to 15.

Question 7

Are RDS Read Replicas synchronous?

Answer 7

No, replication is asynchronous.

Question 8

What is Amazon Aurora?

Answer 8

AWS-optimized database compatible with MySQL and Postgres, high performance and high availability.

Question 9

How many replicas does Aurora support?

Answer 9

Up to 15 with sub-10ms replica lag.

Question 10

How does Aurora handle failover?

Answer 10

Instantaneous failover, 6 copies across 3 AZs.

Question 11

What is Aurora Backtrack?

Answer 11

Restore data to a previous point without using backups.

Question 12

How is RDS/Aurora encrypted at rest?

Answer 12

Using AWS KMS keys defined at launch.

Question 13

How is RDS/Aurora encrypted in-flight?

Answer 13

Using TLS.

Question 14

What is IAM Authentication in RDS?

Answer 14

Use IAM roles to authenticate instead of username/password.

Question 15

What is RDS Proxy?

Answer 15

Fully managed database proxy service for RDS and Aurora databases. It helps improve application scalability, availability, and security, especially for serverless apps like Lambda that need to access databases. Reuse existing connection.

Question 16

Which engines does RDS Proxy support?

Answer 16

RDS & Aurora for MySQL, PostgreSQL.

Question 17

What is ElastiCache?

Answer 17

Managed in-memory cache service for Redis or Memcached.

Question 18

What is the main benefit of using ElastiCache?

Answer 18

Reduce database load and improve application performance.

Question 19

How does ElastiCache help with user sessions?

Answer 19

Stores user session data in-memory for quick access across app instances.

Question 20

Redis vs Memcached: which supports replication?

Answer 20

Redis supports replication and durability; Memcached does not.

Question 21

Which ElastiCache engine supports backup/restore?

Answer 21

Redis.

Question 22

What is Lazy Loading in caching?

Answer 22

Only loads data into cache on request, reducing unused data.

Question 23

What is Write-Through caching?

Answer 23

Updates cache immediately on DB write.

Question 24

What are the main cache eviction strategies?

Answer 24

Explicit delete, LRU eviction (Least Recently Used), TTL expiration.

Question 25

What is TTL in caching?

Answer 25

Time-To-Live: how long data stays in cache before expiration.

Question 26

When should you use Lazy Loading?

Answer 26

When reads are frequent and data doesn't change often.

Question 27

What is Amazon MemoryDB?

Answer 27

Redis-compatible, durable in-memory DB with high throughput and multi-AZ support.