Question

Which of the following is true with respect to strongly consistent read requests from an application to a DynamoDB with a DAX cluster?

A. All requests are forwarded to DynamoDB & results are cached.

B. All requests are forwarded to DynamoDB & results are stored in Item Cache before passing to application.

C. All requests are forwarded to DynamoDB & results are stored in Query Cache before passing to application.

D. All requests are forwarded to DynamoDB & results are not cached.

Answer 1

Correct Answer - D.

For strongly consistent read request from an application, DAX Cluster pass all request to DynamoDB & does not cache for these requests.

Option A is incorrect as Partly correct as for consistent read request from an application, DAX Cluster pass all requests to DynamoDB & does not cache for these requests.

Option B is incorrect as Only for GetItem and BatchGetItem eventual consistent read request, Data is stored in Item Cache.

Option C is incorrect as Only for Query and Scan eventual consistent read request, Data is stored in Query Cache.

For more information on DAX for DynamoDB, refer to the following URL-

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DAX.concepts.html#DAX.concepts.item-cache

DynamoDB Accelerator (DAX) is an in-memory cache for DynamoDB that provides fast and easy access to data. When an application makes read requests to a DynamoDB table that is associated with a DAX cluster, DAX processes the requests and caches the responses for subsequent requests.

With respect to strongly consistent read requests from an application to a DynamoDB table with a DAX cluster, the following is true:

Answer: D. All requests are forwarded to DynamoDB, and results are not cached.

Explanation: Strongly consistent read requests from an application to a DynamoDB table with a DAX cluster are always forwarded to the underlying DynamoDB table for processing. This is because strongly consistent reads require that the data returned is the most up-to-date and accurate version of the data. Therefore, it cannot be cached in the DAX cluster.

In contrast, eventually consistent reads can be cached in the DAX cluster because they are allowed to return data that may not be the most up-to-date version of the data. This can result in faster response times for applications that perform eventually consistent reads.

To summarize, DAX caches responses for eventually consistent read requests, but strongly consistent read requests are always forwarded to DynamoDB for processing and are not cached in DAX.