Which Azure feature allows administrators to set a maximum spending limit to prevent unexpected charges on a subscription?
Azure Cost Management budgets enable you to define a monetary threshold for a subscription, resource group, or management group over a monthly, quarterly, or annual period, and then configure alerts that fire when actual spending reaches a specified percentage of that budget (for example, 90%). These alerts can send email notifications or trigger automated actions, such as a webhook to an automation runbook, making them the correct native service for notifying you when costs approach or exceed your limits. While budgets do not automatically block resource creation by default, they are the primary cost governance tool for setting spending thresholds and alerting, which directly matches the scenario in the question.
Why this answer
Azure Cost Management budgets allow administrators to set spending limits and receive alerts when costs exceed thresholds, preventing unexpected charges. This feature directly controls subscription spending by defining budget amounts and actions, such as disabling resources or sending notifications, when the budget is reached.
Exam trap
The trap here is confusing governance features like Azure Policy (which enforces rules on resource properties) with cost control features, leading candidates to select Azure Policy instead of the correct budget functionality.
How to eliminate wrong answers
Option A is wrong because Azure Policy enforces organizational rules and compliance by evaluating resource configurations, not by setting spending limits or preventing charges. Option C is wrong because Azure Reservations provide discounted pricing for committing to specific services upfront, but they do not set a maximum spending limit or prevent unexpected charges. Option D is wrong because Azure Advisor cost recommendations offer suggestions to optimize spending, but they do not enforce a spending cap or block charges.