I think the key here is to focus on the requirements. It is clearly stated that the requirement is that the strategy meet an RPO of 2 hours and an RTO of 4 hours. Even though option C is the most cost-effective, it is contingent on a few external factors, like the size of the data, the data change rate, etc., which cannot be assumed at the risk of breaching RPO and RTO requirements. So based on that, the most effective option is D.

Answer: C Weird question. Sometimes I think there is no BEST answer and that they were created just to confuse people. Anyway, thinking on cost and the mentioned RPO and RTO, I would still go with C (if they were longer, it would be easier to choose among the questions).

C for me

My answer is B. B is cheapest and it will create only when event occurs. it will complete within 2hours. C and D are costly options compare to BH

AWS often publish this kind of bad framed question. The question is looking for most cost effective solution. So I believe C is the expected answer even it is not complete answer. But C has three big problems: 1. a backup is a backup, if it doesn't provide a way to restore, it is only a backup and is not a complete DR. 2. It doesn't mention the frequency of the backup nor the continuous backup, which means we don't know whether it can meet the 2hr RPO. 3. It doesn’t mention the ECS DR. Well, neither does the other answers. . Aurora global db and DynamoDB global table are apparently more expensive. With the question design, they should be excluded even they are actually complete answers.

Github Copilot answer: The solution you proposed is a good approach for implementing a disaster recovery (DR) strategy. Here's a breakdown of how it works: 1. **AWS Database Migration Service (DMS)**: This service can be used to replicate data from your Amazon Aurora databases in the primary region to the secondary region. This ensures that you have a backup of your data in case of a disaster in the primary region. 2. **Amazon EventBridge and AWS Lambda**: These services can be used together to trigger the replication process whenever there is a change in the Aurora databases. 3. **DynamoDB Streams, EventBridge, and Lambda**: DynamoDB Streams capture table activity, and you can use Lambda functions triggered by EventBridge to process the stream and replicate the changes to DynamoDB tables in the secondary region.

We have no idea the size of the db thus we can't assume we can reach an RTO of 4 hours using backups. D is the cheapest solution out of A, B and D.

https://docs.aws.amazon.com/whitepapers/latest/disaster-recovery-workloads-on-aws/disaster-recovery-options-in-the-cloud.html Thus the correct answer is C, as the minimum RPO for AWS Backup (unless you use Point-in-time recovery) is exactly 2 hours.

Backup restore can take more than 4 hours, so D

The correct answer is in fact D. Though the question asks for a cost effective option. Option C does not guarantee on the mentioned RPO and RTO. So between A and D what is the most cost effective way. D wins as it does not have cost of Cloudfront

AWS often publish this kind of bad framed question. The question is looking for most cost effective solution. So I believe C is the expected answer even it is not complete answer. But C has two big problems: 1. a backup is a backup, if it doesn't provide a way to restore, it is only a backup and is not a complete DR. 2. It doesn't mention the frequency of the backup nor the continues backup, which means we don't whether it can meet the 2hr RPO. . Aurora global db and DynamoDB global table are apparently more expensive. With the question design, they should be excluded even they are actually complete answers.

D is ans Database replication: Aurora global databases and DynamoDB global tables provide automatic, continuous replication across Regions, ensuring an RPO of 2 hours or less. This eliminates the need for manual database setup or complex replication processes. Regional API endpoints: Configuring API Gateway APIs with Regional endpoints in both Regions ensures availability in either Region, supporting a quick RTO of 4 hours. Route 53 failover routing: Route 53 provides a cost-effective and efficient way to switch traffic between Regions during a DR event. It eliminates the need for more expensive services like CloudFront for failover.

d ANS

Its C based on the: "Which solution will meet these requirements MOST cost-effectively?"

The AWS backup based approach is highly cost-effective, employs a backup and restore strategy, and can be designed to comply with cross region backup regulatory requirements. I also explained Aurora Global Database, an Aurora feature which can be utilized when you have strict RTO and RPO requirements. https://aws.amazon.com/es/blogs/database/cost-effective-disaster-recovery-for-amazon-aurora-databases-using-aws-backup/

they mentioned cloud formation, code pipeline and made rto and rpo less strict

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