AZ-305 Practice Question 28: Serverless Plan Selection
Microsoft Azure Solutions Architect Expert (AZ-305) · Test 3 · question 8 of 10
A retailer is building an HTTP API as a .NET isolated Azure Functions app on Linux. The design must satisfy the following:
- The function app must reach an Azure SQL database and a storage account that are exposed only through private endpoints, so it must be integrated with a virtual network. - The API receives no traffic between roughly 21:00 and 07:00, and finance will not approve paying for compute during those hours. - The first requests each morning must not pay a cold-start penalty. - Traffic spikes require scaling out to several hundred instances within a few minutes.
Which hosting plan should you recommend?
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Answer:
Flex Consumption is the plan built for this exact combination and is Microsoft's recommended serverless hosting plan for Functions. It keeps the Consumption plan's scale-to-zero, execution-based billing while adding two things the Consumption plan lacks: virtual network integration, so the app can reach private endpoints, and optional always-ready instances that reduce cold start for a chosen function group. It scales out to as many as 1,000 instances, which covers the morning spike.
Option B fails the first requirement. The Consumption plan does not support virtual networks, so the app cannot reach private-endpoint-only resources at all, and routing outbound traffic through a NAT gateway is a virtual network feature it cannot use either.
Option C is the closest wrong answer and fails on cost. Elastic Premium supports virtual network integration and prewarmed instances, but it always keeps a minimum of one instance running and billed, so the app never costs nothing overnight. That is the very thing finance refused.
Option D is the most expensive version of the same flaw. A Dedicated plan bills for its allocated instances continuously, and Always On explicitly keeps the app warm around the clock, so the ten idle hours are paid for in full every night.