AZ-104 Question 151
Single answerYou are deploying an Azure Virtual Machine Scale Set for a critical web application that experiences unpredictable traffic spikes. The application's CPU usage can suddenly increase when traffic spikes occur. You want to configure the scale set to automatically scale out if CPU utilization remains above 75% for 10 minutes, scale in when it remains below 40% for 10 minutes, and ensure all scale set VMs receive OS patch updates automatically. Which of the following configurations should you implement?
- A
Create the scale set with Automatic OS upgrades disabled, set a scale-out rule for CPU usage above 75% for 10 minutes, and a scale-in rule for CPU usage below 40% for 10 minutes
- B
Create the scale set with Automatic OS upgrades enabled, set a scale-out rule for CPU usage above 75% for 10 minutes, and a scale-in rule for CPU usage below 40% for 10 minutes
- C
Create the scale set with Automatic OS upgrades enabled, set a scale-out rule for CPU usage above 50% for 5 minutes, and a scale-in rule for CPU usage below 50% for 5 minutes
- D
Create the scale set with Automatic OS upgrades disabled, set a scale-out rule for CPU usage above 85% for 15 minutes, and a scale-in rule for CPU usage below 35% for 15 minutes
Show answer and explanation
Correct answer: B
Explanation
Enabling Automatic OS upgrades ensures the VMs receive required OS patch updates without manual intervention. Setting the correct scale-out and scale-in rules (75%/40% for 10 minutes) aligns with the performance requirements of the application. Only the second option meets all these criteria.
- A. Incorrect.
This option meets the scaling thresholds but does not have OS upgrades enabled, failing the requirement for automatic OS patch updates.
- B. Correct.
This option meets both the required CPU thresholds (75% for 10 minutes to scale out, 40% for 10 minutes to scale in) and has Automatic OS upgrades enabled, fulfilling all requirements.
- C. Incorrect.
Although Automatic OS upgrades are enabled here, the scaling thresholds do not match the required 75% (out) and 40% (in) for 10 minutes, making it unsuitable.
- D. Incorrect.
This option disables Automatic OS upgrades and uses different thresholds (85%/35% for 15 minutes) than required, so it does not satisfy the scenario.