AZ-104 Question 152
Select 2You manage a virtual machine scale set (VMSS) hosting a stateless web application with fluctuating user demand. You need to ensure the VMSS automatically adds instances when CPU usage spikes and removes instances when demand falls, all without interrupting the running application. Which two configurations should you implement?
- A
Enable autoscale rules based on CPU metrics
- B
Use rolling upgrades for instance updates
- C
Configure ephemeral OS disks for all VM instances
- D
Enable overprovisioning for the scale set
Show answer and explanation
Correct answers: A, B
Explanation
To automatically scale the virtual machine instances in response to changing load, autoscale rules based on performance metrics are required. Rolling upgrades help update VM instances with little or no service interruption. Ephemeral OS disks and overprovisioning are useful features but do not address the core requirement of automated, non-disruptive scaling.
- A. Correct.
Autoscale rules based on CPU usage allow the scale set to dynamically add or remove instances as usage patterns change.
- B. Correct.
Using rolling upgrades helps ensure updates proceed in batches without taking the entire application offline.
- C. Incorrect.
Ephemeral OS disks can improve performance but do not directly influence uninterrupted scaling or dynamic resource allocation.
- D. Incorrect.
Overprovisioning can speed up deployment times by initially creating extra VMs, but it does not inherently prevent application downtime or address CPU-based scaling events.