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Exam AWS Certified Solutions Architect - Professional topic 1 question 575 discussion

Exam question from Amazon's AWS Certified Solutions Architect - Professional
Question #: 575
Topic #: 1
[All AWS Certified Solutions Architect - Professional Questions]

A company is having issues with a newly deployed serverless infrastructure that uses Amazon API Gateway, Amazon Lambda, and Amazon DynamoDB.
In a steady state, the application performs as expected. However, during peak load, tens of thousands of simultaneous invocations are needed and user requests fail multiple times before succeeding. The company has checked the logs for each component, focusing specifically on Amazon CloudWatch Logs for Lambda.
There are no errors logged by the services or applications.
What might cause this problem?

  • A. Lambda has very low memory assigned, which causes the function to fail at peak load.
  • B. Lambda is in a subnet that uses a NAT gateway to reach out of the internet, and the function instance does not have sufficient Amazon EC2 resources in the VPC to scale with the load.
  • C. The throttle limit set on API Gateway is very low. During peak load, the additional requests are not making their way through to Lambda.
  • D. DynamoDB is set up in an auto scaling mode. During peak load, DynamoDB adjusts capacity and throughput behind the scenes, which is causing the temporary downtime. Once the scaling completes, the retries go through successfully.
Show Suggested Answer Hide Answer
Suggested Answer: C 🗳️
Reference:
https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-request-throttling.html
by Nemer at Aug. 10, 2020, 5:50 p.m.
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proxyolism
Highly Voted 3 years, 10 months ago
the answer is C. question says The company has checked the logs for each component, focusing specifically on Amazon CloudWatch Logs for Lambda. and it means there is no error log from lambda. the company actually did not check API gateway's cloudwatch log. if lambda fails, the company could check it is the lambda problem with cloudwatch logs. furthermore, A is completely wrong because lambda runs pararell with concurrency. and question says this problem only occurs when during maximum loads. if lambda memory is the cause of problem, it can be failed whenever under maximum loads or not.
upvoted 18 times
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Nemer
Highly Voted 3 years, 10 months ago
Fine with C. Nothing wrong with Lambda. Increase API gateway throttle limits.
upvoted 9 times
sam422
3 years, 10 months ago
There are no errors logged in from services or application, why we think gateway throttle errors, it will log if an issue. I go with A
upvoted 2 times
student22
3 years, 9 months ago
C No errors from Lambda because requests were throttled at API Gateway.
upvoted 2 times
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SkyZeroZx
Most Recent 2 years, 1 month ago
Selected Answer: C
Correct is C. If no errors in logs so need increase API gateway throttle limits
upvoted 1 times
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Ni_yot
3 years ago
C makes perfect sense
upvoted 1 times
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AMKazi
3 years, 6 months ago
Ans is C: cannot be D: https://aws.amazon.com/about-aws/whats-new/2017/06/announcing-amazon-dynamodb-auto-scaling/#:~:text=Starting%20today%2C%20when%20you%20create,request%20volumes%2C%20with%20zero%20downtime.
upvoted 1 times
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cldy
3 years, 7 months ago
C is correct.
upvoted 1 times
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AzureDP900
3 years, 7 months ago
C is correct
upvoted 1 times
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WhyIronMan
3 years, 9 months ago
I'll go with C
upvoted 2 times
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Kopa
3 years, 9 months ago
Im for A, was for D but doesnt make sense as if it was scaling issue on Dynamo it will log errors on lambda.
upvoted 2 times
Kopa
3 years, 8 months ago
sorry i mean C
upvoted 1 times
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Waiweng
3 years, 9 months ago
it's C
upvoted 2 times
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kiev
3 years, 9 months ago
It is C. I thought it was A but reading again the last line that says lambda has cloud watch has been checked and there is no problem with lambda implies the problem isn't with lambda. Now between API gateway and Dynamodb, I think it is clear there is a problem with throttle limit in API gateway that's causing the issue.
upvoted 1 times
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Kian1
3 years, 9 months ago
going with C
upvoted 1 times
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Firststack
3 years, 9 months ago
C is correct
upvoted 2 times
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Ebi
3 years, 9 months ago
Answer is C
upvoted 3 times
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kopper2019
3 years, 9 months ago
C API GW limit
upvoted 2 times
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Bulti
3 years, 9 months ago
Answer is C. When throttle limits are low on API Gateway, concurrent requests beyond that threshold limit are dropped and they need to be retried. As a result after repeated retries the request succeeds when the concurrent request count drops below the throttle limit.
upvoted 2 times
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T14102020
3 years, 9 months ago
Correct is C. If no errors in logs so need increase API gateway throttle limits
upvoted 1 times
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