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Exam AZ-303 topic 5 question 17 discussion

Actual exam question from Microsoft's AZ-303

Question #: 17
Topic #: 5

You manage a solution in Azure that consists of a single application which runs on a virtual machine (VM). Traffic to the application has increased dramatically.
The application must not experience any downtime and scaling must be dynamically defined.
You need to define an auto-scale strategy to ensure that the VM can handle the workload.
Which three options should you recommend? Each correct answer presents a complete solution.
NOTE: Each correct selection is worth one point.

A. Deploy application automatic vertical scaling.
B. Create a VM availability set.
C. Create a VM scale set.
D. Deploy application automatic horizontal scaling.
E. Deploy a custom auto-scale implementation.

Show Suggested Answer

Suggested Answer: CDE 🗳️

by Stephan99 at Jan. 4, 2021, 2:42 p.m.

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G_Z

Highly Voted 4 years, 5 months ago

The answers are correct. The B is not correct since there is only one VM.

upvoted 19 times

Ramkid

4 years, 2 months ago

B is not correct as the AS to be defined while creating the VM, not for the existing VMs

upvoted 2 times

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AnonymousJhb

4 years, 2 months ago

Answers: D > Horizontinal Scaling incurs no downtime vs horizontial scaling (resizing vms incurs a vm bounce = downtime) E > Microsoft says "You create rules that define the acceptable performance for a positive customer experience. When those defined thresholds are met, autoscale rules take action to adjust the capacity of your scale set." eg, host-based metrics and | or schedules. C > horizontal scaling is done ONLY in scale sets where all vms are same SKU A > is always wrong because resizing (vertical scaling) a VM incurs downtime which is a requirement defined in the question. B > is wrong because horizontal scaling is ONLY done in scale sets. Av Set has different SKUs and is more for Fault & Update domain tolerance - and has nothing to do with auto scaling. https://docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-autoscale-overview#:~:text=An%20Azure%20virtual%20machine%20scale,the%20performance%20of%20your%20application.

upvoted 11 times

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azurellc

Highly Voted 4 years ago

On exam 5/15/2021

upvoted 6 times

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itvinoth83

Most Recent 3 years, 2 months ago

Appeared in exam on 28-03-2022

upvoted 1 times

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JDS11

3 years, 3 months ago

Selected Answer: CDE

C,D,E - correct answers

upvoted 1 times

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jmay

3 years, 5 months ago

this is a bad question. to enable horizontal scalling, first, the application must can be horizontally scalable. this assumption is not clearly spelt out.

upvoted 1 times

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donathon

3 years, 7 months ago

CDE. A: will have downtime. B: Availability does not scale instances, it only spread it across different fault domain to reduce downtime. Azure provides built-in autoscaling mechanisms that address common scenarios. If a particular service or technology does not have built-in autoscaling functionality, or if you have specific autoscaling requirements beyond its capabilities, you might consider a custom implementation. A custom implementation would collect operational and system metrics, analyze the metrics, and then scale resources accordingly. https://docs.microsoft.com/en-us/azure/architecture/best-practices/auto-scaling

upvoted 1 times

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syu31svc

3 years, 9 months ago

Deploy application automatic vertical scaling – This option incurs a downtime to resize VMs. Create a VM availability set – Availability set cannot scale on its own based on metrics. CDE are right

upvoted 3 times

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pentium75

3 years, 11 months ago

Weird question. But "vertical scaling" causes downtime (thus A is out), and "a VM availability set" doesn't scale (thus B is out). Leaves CDE. The question can be misunderstood as if the solution would have to protect the application from downtime (which these solutions do not necessarily). But it seems to refer to downtime during implementation of the solution, and that is avoided by CDE.

upvoted 2 times

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Alasmindas

4 years, 1 month ago

C,D,E - is correct answer in my opinion. A and B is not correct.

upvoted 2 times

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demonite

4 years, 3 months ago

Answer is correct

upvoted 2 times

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msmannan

4 years, 3 months ago

Answers are correct. Question here is little misleading as always the case with most of MS Qs :) Existing app is running on a single VM. Expectation from the new solution is to auto scale without any app downtime while auto scaling to manage the increased workload. There are two ways this can be achieved: 1) Configure auto scale set with custom scale settings 2) Configure App Service using app service plan and scale up/out configuration.

upvoted 2 times

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jank

4 years, 3 months ago

Given the "Each correct answer presents a complete solution" I think only C is correct, since I cannot apply any kind of (automatic) scaling with a single VM. I think the question is phrased incorrectly.

upvoted 2 times

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qidas

4 years, 4 months ago

Why custom implementation is required?

upvoted 1 times

prashantjoge

4 years, 4 months ago

"You need to define an auto-scale strategy" --- that's part of the question

upvoted 1 times

ruslan_bespalov_netconomy

4 years, 4 months ago

Then why D is considered correct?

upvoted 2 times

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pullarao

4 years, 4 months ago

Correct answer BDE: Didn't mention identical VM in question. Availability set, horizontal scaling and auto scale are correct options

upvoted 1 times

Blimpy

4 years, 4 months ago

nope - to create a new availability set, it would require downtime as the VM will need to be deleted and recreated with the disk to join an AS .. therefore you cannot select B (the question specifies without downtime)

upvoted 4 times

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xaccan

4 years, 4 months ago

Correct C-D-E B and C can't be together for your information. Please study more before going to exam.

upvoted 4 times

pentium75

3 years, 11 months ago

But the question is about three DIFFERENT options. So that "B and C can't be together" is not an argument. Still C-D-E is correct and B is wrong though.

upvoted 1 times

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azurecert2021

4 years, 4 months ago

given answer is correct https://www.examtopics.com/exams/microsoft/az-300/view/4/ I think C,D,E because availability set - the application must "application must not experience any downtime " but a scale set automatically implements placement groups which work in a similar way to availability sets using fault and update zones. MS docs never recommend using scale sets and availability sets together and I dont even think it is possible? D & E because horizontal scaling means increasing the number of instances as opposed to vertical scaling which increases the instances resources.You can use metrics from application insights to trigger scaling. I didnt think both D and E were correct , but seeing that A and B are not correct then I must choose E aswell

upvoted 4 times

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Stephan99

4 years, 5 months ago

Correct answer BCD: Do scale sets work with Azure availability sets? A regional (non-zonal) scale set uses placement groups, which act as an implicit availability set with five fault domains and five update domains. Scale sets of more than 100 VMs span multiple placement groups. For more information about placement groups, see Working with large virtual machine scale sets. An availability set of VMs can exist in the same virtual network as a scale set of VMs. A common configuration is to put control node VMs (which often require unique configuration) in an availability set and put data nodes in the scale set. https://docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-faq

upvoted 4 times

Blimpy

4 years, 5 months ago

to create a new availability set, it would require downtime as the VM will need to be deleted and recreated with the disk to join an AS .. therefore you cannot select B (the question specifies without downtime)

upvoted 6 times

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