Exam AZ-104 topic 5 question 78 discussion

Actual exam question from Microsoft's AZ-104

Question #: 78
Topic #: 5

Note: This question is part of a series of questions that present the same scenario. Each question in the series contains a unique solution that might meet the stated goals. Some question sets might have more than one correct solution, while others might not have a correct solution.
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You have an app named App1 that is installed on two Azure virtual machines named VM1 and VM2. Connections to App1 are managed by using an Azure Load
Balancer.
The effective network security configurations for VM2 are shown in the following exhibit.

You discover that connections to App1 from 131.107.100.50 over TCP port 443 fail.
You verify that the Load Balancer rules are configured correctly.
You need to ensure that connections to App1 can be established successfully from 131.107.100.50 over TCP port 443.
Solution: You create an inbound security rule that denies all traffic from the 131.107.100.50 source and has a priority of 64999.
Does this meet the goal?

A. Yes
B. No

Show Suggested Answer

Suggested Answer: B 🗳️

by omw2wealth at Sept. 28, 2021, 1:13 p.m.

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Zarzi

Highly Voted 3 years, 7 months ago

i'm not a robot

upvoted 45 times

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GBAU

Highly Voted 2 years, 4 months ago

Selected Answer: B

Answer B (No) When an Azure Load Balancer get created, it will probe backend to detect if the backend service is healthy or not, the probe packet is sent from source address "AzureLoadBalancer", the IP address of "AzureLoadBalancer" is always 168.63.129.16. https://msazure.club/addendum-of-azure-load-balancer-and-nsg-rules/ What is happening here is the LB Health Probe of TCP 443 to VM1 & VM2 are getting blocked by Rule 200 so it thinks both VM1 and VM2 are down. Hence App1 is failing as the LB won't direct any 443 traffic anywhere as it considers all Hosts are down. Make a new rule above 200 or move rule 65001 up to <200, so the Health Probe will start working again, it will find a health host and start to direct 443 traffic from 131.107.100.50 to it. App1 is alive!

upvoted 27 times

Student2023

2 years, 2 months ago

For this question (and other questions with similar context) this is the first time the explanation made total sense. Thank you!

upvoted 3 times

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[Removed]

Most Recent 7 months, 3 weeks ago

Selected Answer: B

B is correct You create an inbound security rule that allows any traffic from the AzureLoadBalancer source and has a priority of 150.

upvoted 1 times

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aikooo

1 year, 2 months ago

I think answer is B

upvoted 1 times

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Zuurpruim

1 year, 9 months ago

Selected Answer: B

"Attach Network Interface" is not greyed out which means the VM is powered off. That is the reason it's not working.

upvoted 2 times

conip

1 year, 8 months ago

I think sticking to the reason of greyed out "attach button" is misleading. APP is on VM1 and VM2 - even if VM2 is shutdown it should still be served by VM1 - they do share NSG as its attached to subnet so we still need to focus on NSG logic

upvoted 2 times

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