Your application currently leverages AWS Auto Scaling to grow and shrink as load Increases/ decreases and has
been performing well Your marketing team expects a steady ramp up in traffic to follow an upcoming
campaign that will result in a 20x growth in traffic over 4 weeks Your forecast for the approximate number of
Amazon EC2 instances necessary to meet the peak demand is 175.
What should you do to avoid potential service disruptions during the ramp up in traffic?
A.
Ensure that you have pre-allocated 175 Elastic IP addresses so that each server will be able to obtain one as
it launches
B.
Check the service limits in Trusted Advisor and adjust as necessary so the forecasted count remains within
limits.
C.
Change your Auto Scaling configuration to set a desired capacity of 175 prior to the launch of the marketing
campaign
D.
Pre-warm your Elastic Load Balancer to match the requests per second anticipated during peak demand
prior to the marketing campaign
Answer should be B, as the EC2 limit per region is max 20. You will need to fill a Amazon EC2 instance request form to increase the EC2 instances to 175.
http://aws.amazon.com/ec2/faqs/#How_many_instances_can_I_run_in_Amazon_EC2
I dont think the answer can be D, as the question says “expects a steady ramp up in traffic to follow an upcoming campaign that will result in a 20x growth in traffic over 4 weeks”. To pre-warm your ELB, you have to put in a request to AWS. You cant do it.
Assuming permission to have more than 20 EC2’s has already been granted, the answer would be D, but again that assumes that a request has been sent to AWS, as Khozi mentioned.
Seth,
The purpose of the Pre-warm ELB is to be prepared for the sudden traffic since the traffic expected is steady it doesn’t suit for this question.
I dont think Trust Advisor will help here. I think the right answer is D.
Besides, I think B is wrong as you can’t adjust the limits in Trust Advisor, you would need to open a case with AWS to request a raise on the limits.
Pre-Warming the Load Balancer
Amazon ELB is able to handle the vast majority of use cases for our customers without requiring “pre-warming” (configuring the load balancer to have the appropriate level of capacity based on expected traffic). In certain scenarios, such as when flash traffic is expected, or in the case where a load test cannot be configured to gradually increase traffic, we recommend that you contact us to have your load balancer “pre-warmed”. We will then configure the load balancer to have the appropriate level of capacity based on the traffic that you expect. We will need to know the start and end dates of your tests or expected flash traffic, the expected request rate per second and the total size of the typical request/response that you will be testing.
From this explanation , i would think answer is “D”
B is the correct answer. If not checked and adjusted, this would definitely cause a service disruption.
A is incorrect, I don’t believe you can automatically attach Elastic IP’s in an Auto Scaling Group. Also, this use of an EIP for every instance is not recommended by AWS.
C is incorrect as this would ensure 175 instances are running.
D is incorrect. The question explicitly states “Your marketing team expects a steady ramp up in traffic” which means pre warming the ELB is not required.
D is the correct answer.
B is incorrect because you can’t setup the limit or increase it, (You can’t adjust any resource limit by yourself) you have to open the case for it.
D
Pre-Warming the Load Balancer
Amazon ELB is able to handle the vast majority of use cases for our customers without requiring “pre-warming” (configuring the load balancer to have the appropriate level of capacity based on expected traffic).
https://aws.amazon.com/articles/1636185810492479#pre-warming
I vote for B.
ELB prewarming is not needed as the traffic ramp up is over 4 weeks. Checking service limits and getting approval for bigger limits is what will do the trick
It should be B ( I know there is still room for improvement in the statement itself to bring clarity ), but what JK has said above about each possible options is correct and makes sense in this context.
d
B is not an answer, even we can adjust max number of instances to 175 in autoscaling group, by pre-assuming we have limit up to/ more than 175. And here also we should not avoid potential service disruptions during the traffic by setting limits to services (Trusted Advisor).
D is the answer, We must pre-warm the ELB, as in the question mentioned, the traffic can
forecast to approximate instances and should not be the bottleneck for the service disruptions.
Sorry, the answer would be option B. Pre-warming ELB is necessary if there is a sudden spike in the traffic not during steady ramp-up.
The answer is D.
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Obviously D. Trusted Advisor is not even available until you upgrade your support plan and you can’t just adjust it as stated in option B.
Amazon ELB is able to handle the vast majority of use cases for our customers without requiring “pre-warming” (configuring the load balancer to have the appropriate level of capacity based on expected traffic). In certain scenarios, such as when flash traffic is expected, or in the case where a load test cannot be configured to gradually increase traffic, we recommend that you contact us to have your load balancer “pre-warmed”. We will then configure the load balancer to have the appropriate level of capacity based on the traffic that you expect. We will need to know the start and end dates of your tests or expected flash traffic, the expected request rate per second and the total size of the typical request/response that you will be testing.\
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They are suggesting prewarming
I go with Answer D
Answer is B
D – Amazon ELB is able to handle the vast majority of use cases for our customers without requiring “pre-warming” (configuring the load balancer to have the appropriate level of capacity based on expected traffic).
See: https://aws.amazon.com/articles/1636185810492479#pre-warming
B is absolutely wrong, TrustedAdvisor checks network service ports, and database connector ports.
C is the answer.
D is wrong because this traffic acceleration is over 28 days, not a huge sudden spike. This means no need to pre-warm ELB.
C is the answer
D
The answer is D.
Answer will be : D as trusted advisor not related at all to the ramp-up of the load in peaks
Of course it’s B.
Trusted Adviser shows the soft limits and you can click the link for the EC2 size you need to increase in that tool and create a ticket to increase the limit from the default 20 to the higher number you need to meet the demands of the ramp-up; 175.
Answer B is wrong because you can pre-warm ELBs all day, but the service will fall over when it adds instances up to the default limit (20) and can’t add any more.
Answer C won’t help because you can create an ASG with min and max numbers higher than the limit in Trusted Adviser.
Correction….I meant “D”/Prewarm ELBs is wrong
“In certain scenarios, such as when flash traffic is expected, or in the case where a load test cannot be configured to gradually increase traffic, we recommend that you contact us to have your load balancer “pre-warmed”. – the question says the steady growth is expected, not flash.
I vote for B. The default limit is 20 instances per AZ and needs to be increased explicitly.
B, obviously
There is no need to pre-warm the ELB since it’s a steady ramp up of the traffic.
It has to be B – Trusted Advisor- it shows the Service Limits. Normally you will not have that much limit in your account.
Not A – don’t need Elastic IP.
Not C – Autoscaling desired capacity should not be 175 – that can only be Max (it is gradual increase over 4 weeks)
Not D – ELB pre-warming is necessary when sudden spikes are expected not gradual increase.
B
C is wrong because 175 is the max limit not the desired.
D is wrong because Pre-warming the ELB is only needed when the traffic spike is sudden.