Exam AZ-301 topic 16 question 1 discussion

Ensure that the number of compute nodes of the front-end and the middle tiers of the payment processing system can increase or decrease automatically based on CPU utilization.

A. Azure Kubernetes Service (AKS) > Can be ruled out. Requirement says to host the middle tier on VMs. B. virtual machine scale sets > Fullfills the requirement of increasing or decreasing automatically based on CPU utilization, can be used together with availability zones to reach 99.99% SLA C. availability sets > Doesn't provide a 99.99% SLA "only" 99.95% D. App Service Environments (ASEs) > Can be ruled out for the same reason as A. Conclusion: > Answer B. is correct

B. is correct answer.

App Service Environments (ASE) can be deployed into Availability Zones (AZ). First: Whenever possible, Azure managed services must be used to minimize management overhead. Second: Whenever possible, costs must be minimized.

Ensure that the number of compute nodes of the front-end and the middle tiers of the payment processing system can increase or decrease automatically based on CPU utilization. Ensure that each tier of the payment processing system is subject to a Service Level Agreement (SLA) of 99.99 percent availability As Availability Set gives only 99,95 we need to have VM scale set with zones which gives 99,99

Everyone repeat after me and burn this into your mind: RA-GRS IS MORE EXPENSIVE THAN GRS. This makes sense too, because with RA-GRS, Microsoft must make sure that data is available to be read from multiple locations. This means more networking and added complexity. With GRS, they activate a secondary entry-point when they monitor an issue with the primary region: single entrypoint and less networking and less complexity = less expensive.

Answer is correct. Scale Sets

"Host the middle tier of the payment processing system on a virtual machine." Answer is correct

I sort-of doubt AKS, VMSS, and availability sets as per migration requirements: - Infrastructure services must remain available if a region or a data center fails... - Whenever possible, Azure managed services must be used ... AKS is a managed service, but no option could cover regional failure. VMSS and Availability sets are not a managed service; no option could cover regional failure. ASE is managed service, and has option to cover regional failure. See: https://docs.microsoft.com/en-us/azure/app-service/environment/intro But, why a cross regional managed service w/ SLA lower than 99.99% is a puzzle in my mind: https://azure.microsoft.com/en-us/support/legal/sla/app-service/v1_4/ Maybe Azure are talking when some customer only config single region?

B. virtual machine scale sets

I think the answer is correct. According to this link: https://azure.microsoft.com/en-us/support/legal/sla/virtual-machines/v1_9/ SLA for Virtual Machines Last updated: January 2020 *For all Virtual Machines that have two or more instances deployed across two or more Availability Zones in the same Azure region, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.99% of the time. So we can deploy a scale set on two availability zones to achieve a SLA of 99.99%

the given answer is correct

Answer is correct as per the requirement - Host the middle tier of the payment processing system on a virtual machine.

I wonder if it's AKS because: Minimize the effort required to modify the middle tier API and the back-end tier of the payment processing system. - easy with containers. AKS uses scale set internally ...