Elasticache

Question 1

There are 3 design patterns for Elasticache, what are they and what do they do?

Answer 1

Lazy Loading: All read data is stored in cache - but cache can become stale
Write Through: Adds or updates data in cache when data is written to DB - no stale data
Session Store: Supports TTL. Use for temporary session data.

Question 2

Do either of the Elasticache engines support IAM authorizations?

Answer 2

No. Neither.

Question 3

By default - is Elasticache:

• Multi AZ
• Encrypted at Rest
• Encrypted in Transit

Answer 3

it can be multi-AZ, but this needs to be enabled.

Data is not encrypted at rest or in transit by default.

Question 4

How do you authenticate to Reddis and Memcached

Answer 4

ReddisAuth (Username/Pwd) and SASL for Memcached

Question 5

What is the cost model for elasticache

Answer 5

Pay per hour based on EC2 instance type

Question 6

Is a cached version of data considered an authoritative version? If so, under what conditions?

Answer 6

A Cached version is considered authoritative until the ttl expires