Exam AWS Certified Solutions Architect - Professional topic 1 question 76 discussion

D is correct. It would be more costly to scale the read and write of the DynamoDB for the million visitors peak time, while you can offload the read and write using SQS. That will reduce the high cost of read/write on DyDB.

The answer is not C if DynamoDb is configured to auto-provision WCU then a burst in traffic is going to be very expense as million of users are going to make the WCU very high to handle the load, if DynamoDb has fixed WCU then the high sudden volume will cause errors. SQS is always better at dealing with normalizing bursts in traffic therefore D.

D. Use CloudFront and an Elastic Load Balancer in front of an auto-scaled set of web servers, the web servers will first call the Login With Amazon service to authenticate the user, the web servers win process the users vote and store the result into an SQS queue using IAM Roles for EC2 Instances to gain permissions to the SQS queue. A set of application servers will then retrieve the items from the queue and store the result into a DynamoDB table.

Design B is not as suitable for this scenario because it does not use any load balancing. This means that if the website receives a large number of visitors, the web servers could become overloaded. This could lead to performance problems, such as slow loading times or even outages. Design D uses CloudFront and an Elastic Load Balancer to distribute traffic across the web servers. This helps to prevent any single web server from becoming overloaded, which can improve performance and prevent outages. In addition, design D uses SQS to buffer the votes. This helps to prevent the web servers from being overloaded by a large number of votes. This can also improve performance by reducing the number of requests that need to be made to the web servers. Therefore, design D is a better choice for this scenario because it uses load balancing and SQS to improve performance and prevent outages.

B how to comunicate with IAM Role ? is correct C is incorrect for cost insted of use SQL D is correct because use SQS for not provisioned WCU in DynamoDB is more cost

A. Read the question, DynamoDB is a component to be used in my mind. Quickly scan the answers, all other answers use DybnamDB. So I killed this answer first. B. Looks very good, but how to use IAM roles in this setup? C. Not a bad solution. D. This is a better solution than C, with SQS, to decouple data provider and consumer the DynamoDB can be provisioned without considering accommodating the peak traffic.

DDDDDDDDD

Why not B? It's totally feasible. Millions of visitors + keeping the cost low => Serverless, CloudFront -> S3 (JS) -> DDB.

C is correct. https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/S3Export.html Log data can take up to 12 hours to become available for export. For near real-time analysis of log data, see Analyzing log data with CloudWatch Logs Insights or Real-time processing of log data with subscriptions instead. Only C meets the RPO/RTO requirements.

D. Use CloudFront and an Elastic Load Balancer in front of an auto-scaled set of web servers, the web servers will first call the Login With Amazon service to authenticate the user, the web servers win process the users vote and store the result into an SQS queue using IAM Roles for EC2 Instances to gain permissions to the SQS queue. A set of application servers will then retrieve the items from the queue and store the result into a DynamoDB table.

OK, I'll go with D. Both B and C can be expensive if using on-demand capacity mode of DynamoDB. But by adding some retry logic, I think I can work.

I'm not sure which is right. It seems people don't choose A or C, because it is said to be expensive. But using on-demand capacity mode of DynamoDB, in US East (N. Virginia) Region, it's only $1.25 per million write request units. So with millions of visitors and 1 vote for each visitor, it only costs less than $20 for each performance. And another thing, aggregation is needed after vote, but I don't think DynamoDB is good at aggregation. So is DynamoDB really a good choice?

Answer D, using SQS the request rate will get flattened and make proper IOPS of DynamoDB to write and read data for millions of users.

D is correct, agree, SQS is better than auto-provision WCU for dynamodb

D http://jayendrapatil.com/aws-storage-options-whitepaper/

Answer is D Keyword is "After the voting is completed the page will display the vote totals"

Answer D: Use CloudFront and an Elastic Load Balancer in front of an auto-scaled set of web servers, the web servers will first call the Login. With Amazon service to authenticate the user, the web servers would process the users vote and store the result into an SQS queue using IAM Roles for EC2 Instances to gain permissions to the SQS queue. A set of application servers will then retrieve the items from the queue and store the result into a DynamoDB table