Exam AWS Certified Solutions Architect - Associate SAA-C02 topic 1 question 278 discussion

C. common read requests: cache A is wrong: submillisecond : Lasting less than a millisecond. But all Aurora Replicas return the same data for query results with minimal replica lag. This lag is usually much less than 100 milliseconds after the primary instance has written an update. Replica lag varies depending on the rate of database change. That is, during periods where a large amount of write operations occur for the database, you might see an increase in replica lag. D is for: Application monitoring Security information and event management (SIEM) Search Infrastructure monitoring

Why admin's answer is A and link provided is pointing to elastic cache Correct Answer: A Reference: https://aws.amazon.com/redis/ Answer is clearly c , Sub-millisecond is supported by elastic cache only

C is the answer

Amazon ElastiCache is a fully managed in-memory data store and cache service. ElastiCache can be used to cache requests to an Amazon RDS database through application configuration. This can greatly improve performance as ElastiCache can return responses to queries with sub-millisecond latency.

response times of less than a millisecond for "frequent read requests". cache, hence redis

Why are the admins ans like this

Redis can serve frequently requested items at sub-millisecond response times

Correct Answer: C. Build a database cache using Amazon ElastiCache. Ref : https://aws.amazon.com/redis/ Redis is a great choice for implementing a highly available in-memory cache to decrease data access latency, increase throughput, and ease the load off your relational or NoSQL database and application. Redis can serve frequently requested items at sub-millisecond response times

C) CORRECT ---> a) we don't replica of Amazon RDS, but Full Fledged RDS, so not correct b) insuffisient info c) Amazon ElastiCache.: Could be relational d) Amazon Elasticsearch is a NON-Relational DB so incorrect

It says the correct answer is A but the reference is for redis...

with "a small percentage of stale data returned in the database reads is acceptable", it should be a cache!

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Maybe you must choose C or D.

C as its about the response time ..

Question states COMMON Read Queries. Which is indication for Cache and stale data is acceptable which is a slight drawback of Cache. All answers hints towards Cache. Read Replica is for HA or duplicate reads, it's purpose is not for stale data.

C Relational databases are a cornerstone of most applications. When it comes to scalability and low latency though, there’s only so much you can do to improve performance. Even if you add replicas to scale reads, there’s a physical limit imposed by disk based storage. The most effective strategy for coping with that limit is to supplement disk-based databases with in-memory caching.

Keywords: Common Read Requests ==== If they are common then its elasticache