Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 714 discussion

Option B is correct because can use "RequestCountPerTarget" to identify the amount of requests for each EC2 instance. Then use "least outstanding requests algorithm" to route to targets with the lowest number of in progress requests. Option D is wrong because "RequestCount" cannot identify the amount of requests for each EC2 instance. "RequestCount" is for the whole ALB.

Option B would be the correct choice

D is correct. https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-cloudwatch-metrics.html ActiveConnectionCount - The total number of concurrent TCP connections active from clients to the load balancer RequestCountPerTarget - The average request count per target, in a target group Both metrics do not show stage of every target. RequestCount - The number of requests processed over IPv4 and IPv6. This metric is only incremented for requests where the load balancer node was able to choose a target. We can say how many requests go to targets. TargetResponseTime - The time elapsed, in seconds, after the request leaves the load balancer until the target starts to send the response headers. We have metric to get statistics for every target/instance. In fact Item D is correct

Actually ,I now vote for B and not D

I will go with D since the question asks for the target response.

D will be correct if change ReqeustCount to RequestCountPerTarget. RequestCount applies to the ALB rather than individual targets, making it unsuitable for identifying overloaded instances. ActiveConnectionCount: This metric indicates the current number of active TCP connections. It complements RequestCountPerTarget by helping identify instances that might be overwhelmed with connections, even if their request count seems moderate.

AnswerB

Option B

IMO the correct answer is option D: This is from an earlier version of the AWS documentation on ALB target groups - for some reason they removed this information in the current revision: "Consider using least outstanding requests when the requests for your application vary in complexity or your targets vary in processing capability. Round robin is a good choice when the requests and targets are similar, or if you need to distribute requests equally among targets. You can compare the effect of round robin versus least outstanding requests using the following CloudWatch metrics: RequestCount, TargetConnectionErrorCount, and TargetResponseTime." https://web.archive.org/web/20200426172626/https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-target-groups.html#modify-routing-algorithm

I think TargetResponseTime is the best indicator for telling is a server is overloaded or not

distribute the number of requests among instances

https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-cloudwatch-metrics.html To understand the types

The question is not asking for better performance in response time. It is just simply asking to distribute the number of requests among instances. So B seems more logical.

The least outstanding requests routing algorithm routes requests to the targets with the lowest number of in progress requests > https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-target-groups.html

D>>> The least outstanding requests routing algorithm routes requests to the targets with the lowest number of in progress requests > https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-target-groups.html

Why not D?