AZ-305 Metric Alert Practice Question
Your company has an Azure subscription with 100 virtual machines. You need to monitor the performance of these VMs and be alerted when the average CPU usage across a set of VMs exceeds 80% for 10 minutes. The set of VMs is defined by a tag (Environment=Production). Which Azure Monitor solution should you implement?
⚠ Common exam trap
The trap is that candidates often assume a metric alert rule scoped to a resource group with tag filtering can aggregate metrics across VMs. However, metric alerts evaluate each VM individually, not the average across the set. The correct approach is to use a Log Analytics query to compute the aggregate and trigger a log alert.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a Log Analytics query to calculate average CPU and set a log alert.
The requirement is to alert when the average CPU usage across a set of VMs (tagged Environment=Production) exceeds 80% for 10 minutes. Metric alert rules (including dynamic thresholds) evaluate per resource, not across multiple resources. Option D uses a Log Analytics query to calculate the average CPU usage across all VMs with the specified tag and then creates a log alert based on that query, which correctly aggregates the metric. Therefore, Option D is the correct solution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Azure Monitor VM Insights to visualize performance and set alerts per VM.
Why it's wrong here
VM Insights alerts are configured per VM, so they cannot evaluate an average across the tag-defined set of 100 machines. It is tempting because VM Insights visualises performance and dependency data, and it would be correct when the requirement is per-VM performance trending rather than a multi-resource metric alert.
- ✗
Create a metric alert rule with a dynamic threshold and scope it to a resource group containing Production VMs.
Why it's wrong here
Dynamic thresholds learn each resource's baseline and alert on deviations, not a fixed 80% average across the tagged set; scoping to a resource group also ignores the tag. Dynamic thresholds suit workloads with fluctuating patterns where static values cause noise, not this explicit 80% aggregate rule.
- ✗
Create a metric alert rule with a static threshold of 80% for each Production VM individually.
Why it's wrong here
Per-VM alerts fire on each machine's CPU, not the aggregate across the tagged set, so the 80% average condition is never evaluated. Targeting individual VMs is right when each host needs its own threshold, but here the requirement is a single alert over the Environment=Production group.
- ✓
Use a Log Analytics query to calculate average CPU and set a log alert.
Why this is correct
A Log Analytics query aggregates CPU across the tag-scoped VMs and a log alert fires when the average exceeds 80% for 10 minutes. Metric alerts cannot natively average across a dynamic tag-defined VM set, so the query satisfies the grouping constraint.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-305 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AZ-305 exam.