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Exam 70-487 topic 1 question 36 discussion

Actual exam question from Microsoft's 70-487

Question #: 36
Topic #: 1

You are developing a Microsoft Azure web application. The application will be deployed to 20 web role instances. A minimum of 18 running instances is needed to meet scaling requirements.
You need to configure the application so that upgrades are performed as quickly as possible, but do not violate scaling requirements.
How many upgrade domains should you use?

A. 1
B. 2
C. 5
D. 10

Show Suggested Answer

Suggested Answer: C 🗳️
The .csdef is only used for Cloud Services, not for VMs. So regardless of what you set or even how you try to do it, Azure VM UDs come in groups of 5. With 18
VMs, that means you'll have 5 UDs. UD0 "" to "" UD4 like the following:

VMUpdate Domain -

VM00 -

VM11 -

VM22 -

VM33 -

VM44 -

VM50 -

VM61 -

VM72 -

VM83 -

VM94 -

VM100 -

VM111 -

VM122 -

VM133 -

VM144 -

VM150 -

VM161 -
VM172

by Andi7 at Nov. 19, 2019, 6:33 p.m.

Comments

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Andi7

Highly Voted 5 years, 6 months ago

should be 10

upvoted 15 times

abalone

5 years, 6 months ago

agree, 10.

upvoted 4 times

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fallingsappy

5 years, 5 months ago

no, its 5, because they come in group of 5, so we need 5 domains: 5*5 = 25

upvoted 1 times

tiger25

5 years, 4 months ago

"they come in group of 5" - proofs?

upvoted 3 times

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zimzimzimma

4 years, 8 months ago

If they come in groups of 5, the minimum of 18 doesn't make sense, it would be a minimum of 15 or else a group of 5 wouldn't be optimal since the minimum is 18 so one would choose 20 so you pay too much.

upvoted 1 times

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Karel_Gott

Highly Voted 5 years, 2 months ago

The answer is incorrect. Certainly we need 10 upgrade domains. He's a good source https://blog.abelotech.com/posts/windows-azure-fault-and-upgrade-domain/. With 5 upgrade domains it would be distributed like 4, 4, 4, 4, 4 (4 roles for each upgrade domain) - but as you can read in the source I posted - "During deployment all instances of the upgraded role that belongs to the first upgrade domain are stopped, upgraded, and brought back online." - this says that all 4 roles within upgrade domain will be down altogether and therefore there will be only 16 instances running (however, we need 18 - so we need more upgrade domains -> 10).

upvoted 6 times

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ngoanmt

Most Recent 4 years, 7 months ago

The answer should be 10. If you have 20 instances and use 10 upgrade domains --> each upgrade domain will be distributed with 2 instances. When one upgrade domain is in the process, all its instances will be stopped. --> in this case, you lose 2 instances each time --> there is 20-2=18 instances working.

upvoted 2 times

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Dreamchaser1980

4 years, 8 months ago

If you use 10 upgrade domains each upgrade domain will have two web role instances. Because Windows Azure distributes instances of a role evenly (when possible) across a set number of upgrade domains. During deployment all instances of the upgraded role that belongs to the first upgrade domain are stopped, upgraded, and brought back online. Once they are back online, the process is repeated for the second upgrade domain (all roles stopped, upgraded and brought back online), the third upgrade domain and so on until all instances in all upgrade domains have been upgraded. So in this case because each upgrade domains has two web role instances, two web role instances are stopped each time. https://blog.abelotech.com/posts/windows-azure-fault-and-upgrade-domain/

upvoted 2 times

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FrankINS

4 years, 9 months ago

*********How to calculate********* ----- 1. Calculate difference: ----- 20 web role instances 18 minimum running instancess = Difference of 2 ----- 2. Calculate answer: ----- Total / difference = answer. 20 / 2 = 10

upvoted 2 times

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Nayyar

5 years, 3 months ago

web role is iis instance and upgrade domain is logical unit of deployment and default is 5 domains now we need to distribute instances into these 5 logical units 1UD 2UD 3UD 4UD 5UD 4 instances 4 instances 4 instances 4 instances 2 instances It can be manage in 5 https://blog.abelotech.com/posts/windows-azure-fault-and-upgrade-domain/

upvoted 2 times

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this_is_sparta

5 years, 4 months ago

Answer is "B. 2". We need "A minimum of 18 running instances", so we can at max stop two of our 20 instances for an upgrade at the same time to meet this requirement.

upvoted 2 times

this_is_sparta

5 years, 3 months ago

I was wrong. Answere is 10.

upvoted 1 times

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tiger25

5 years, 4 months ago

It's clearly answer D, 10 upgrade domains needed.

upvoted 5 times

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soni

5 years, 4 months ago

5 upgrade domains and 10 instances means each domain containing 2 instances. As we know updating a Cloud Service involves updating one upgrade domain at a time. With 5 upgrade domains that would mean 2 of the instances will be updated while remaining 8 will keep on working

upvoted 1 times

TinaZh

5 years, 4 months ago

in this question 20 web role instances and minimum of 18 running instances, not 10

upvoted 2 times

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