Caching

Question 1

External caching

Answer 1

cache data that’s going to be returned to users (images, videos, static content)

Question 2

Internal caching

Answer 2

• used to speed up databases

- The less we talk to the database, the better

Question 3

What do caches help with?

Answer 3

Speed. Put them everywhere, and favor answers that use a cache.

Question 4

CloudFront for caching

Answer 4

• External cache
• CDN
• improves delivery times by delivering data, apps, APIs to edge locations globally to reduce latency

Question 5

What kind of cache is ElastiCache?

Answer 5

• Internal cache

Question 6

Global Accelerator as a Cache

Answer 6

speeds up external connections

Question 7

How can you put a secure connection on S3 static websites?

Answer 7

CloudFront

• attach a custom SSL certificate
• or create signed URLs or signed cookies

Question 8

Is CloudFront global distribution used for blocking or picking countries?

Answer 8

No, you can only pick continents (use WAF instead)

Question 9

How do you block individual countries?

Answer 9

• Use WAF

- CloudFront is only good at continents

Question 10

CloudFront TTL

Answer 10

Time to live expiry for content expiration

Question 11

For the exam, how can you solve every sort of external customer performance issue?

Answer 11

Put CloudFront in front of the application

Question 12

What is the main purpose of CloudFront edge locations?

Answer 12

Speed

Question 13

Can you do CloudFront on-prem?

Answer 13

Yes. On-Prem and AWS.

Question 14

Can you pick a specific edge location?

Answer 14

No

Question 15

What is ElastiCache?

Answer 15

a managed version of two open source technologies:

• memcached
• redis

it sits in front of a relational database

Question 16

Memcached

Answer 16

• simple database caching solution
• not a database by itself
• no failover
• single AZ
• no backups

Question 17

Redis

Answer 17

• supported as a caching solution
• standalone NoSQL db
• failover support
• can be multi-AZ
• supports backups*

Question 18

Dynamo DB Accelerator (DAX)

Answer 18

Can reduce Dynamo DB response times from milliseconds to microseconds.

• highly available
• lives inside a VPC you specify
• you determine node size & count, TTL for data, and maintenance windows

Question 19

Which caching solution can be a standalone DB with multi-AZ and backups?

Answer 19

Redis

Question 20

How do you fix IP caching?

Answer 20

Global Accelerator - it allows users to use the same 2 static IP addresses for the Elastic Load Balancer (even if they change behind the scenes)

Question 21

Weighted Pools

Answer 21

Global Accelerator feature - you can create weighted groups behind IPs to test out new features or handle failure in your environment

Question 22

Caching Exam tips - Questions to ask?

Answer 22

1) Can it be cached?
2) Will it benefit this architecture?
3) How does content in the cache get updated (TTLs)
4) Does the caching help with anything other than speed?

Question 23

Cases where caching helps with more than just speed

Answer 23

• CloudFront + WAF -> Security

- Global Accelerator -> IP Caching fix

Question 24

What is the only option for adding HTTPS to a static website being hosted by S3?

Answer 24

CloudFront

Question 25

When you see “in memory DB” what do you think of?

Answer 25

a NoSQL option like Redis or DynamoDB

Question 26

If asked to pick between Redis or DynamoDB

Answer 26

Pick DynamoDB