- A
Heartbeat | summarize LastSeen=max(TimeGenerated) by Computer | where LastSeen < ago(15m)
This query uses the Heartbeat table to identify the most recent signal from each VM and filters for machines whose latest heartbeat is older than 15 minutes. That is the correct pattern for detecting VMs that are no longer reporting to Log Analytics or Azure Monitor. It is practical, concise, and directly aligned to troubleshooting agent connectivity or VM availability.
- B
AzureActivity | where OperationNameValue contains 'Heartbeat' | summarize count() by ResourceGroup
Why wrong: AzureActivity tracks control-plane operations, not VM heartbeat telemetry, so it will not identify silent agents.
- C
Perf | where CounterName == '% Processor Time' | summarize avg(CounterValue) by Computer
Why wrong: Perf is useful for performance counters, but CPU data does not indicate whether the VM has stopped sending heartbeat records.
- D
SecurityEvent | where EventID == 4624 | summarize count() by Computer
Why wrong: SecurityEvent contains Windows security logs and successful sign-ins, which are unrelated to heartbeat reporting status.
Quick Answer
The correct answer is `Heartbeat | summarize LastSeen=max(TimeGenerated) by Computer | where LastSeen < ago(15m)`. This query works because the Heartbeat table logs a signal from Azure Monitor agents every five minutes by default, so summarizing the maximum `TimeGenerated` per computer and filtering for values older than 15 minutes directly identifies VMs that have missed at least three consecutive heartbeats, indicating they are likely offline. On the AZ-104 exam, this tests your ability to use the `summarize` operator with `max()` to find the most recent event and then apply a time filter with `ago()`—a common pattern for monitoring agent health. A frequent trap is forgetting that `ago(15m)` looks backward from the current time, not from a fixed point, or using `min()` instead of `max()`, which would return the first heartbeat rather than the last. Remember the memory tip: “Max for the latest, ago for the gap”—use `max(TimeGenerated)` to get the most recent ping, then `ago(15m)` to catch the missing ones.
AZ-104 Monitor and Maintain Azure Resources Practice Question
This AZ-104 practice question tests your understanding of monitor and maintain azure resources. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A help desk analyst wants a query in Log Analytics that returns Azure virtual machines that have stopped sending a heartbeat for more than 15 minutes. Which KQL query should the analyst run?
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
Heartbeat | summarize LastSeen=max(TimeGenerated) by Computer | where LastSeen < ago(15m)
Option A is correct because the Heartbeat table in Log Analytics records a heartbeat signal from Azure Monitor agents every 5 minutes by default. The query uses `summarize` to find the latest `TimeGenerated` per computer, then filters with `where LastSeen < ago(15m)` to identify VMs that have not sent a heartbeat in over 15 minutes, indicating they are likely offline or unresponsive.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Heartbeat | summarize LastSeen=max(TimeGenerated) by Computer | where LastSeen < ago(15m)
Why this is correct
This query uses the Heartbeat table to identify the most recent signal from each VM and filters for machines whose latest heartbeat is older than 15 minutes. That is the correct pattern for detecting VMs that are no longer reporting to Log Analytics or Azure Monitor. It is practical, concise, and directly aligned to troubleshooting agent connectivity or VM availability.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
AzureActivity | where OperationNameValue contains 'Heartbeat' | summarize count() by ResourceGroup
Why it's wrong here
AzureActivity tracks control-plane operations, not VM heartbeat telemetry, so it will not identify silent agents.
- ✗
Perf | where CounterName == '% Processor Time' | summarize avg(CounterValue) by Computer
Why it's wrong here
Perf is useful for performance counters, but CPU data does not indicate whether the VM has stopped sending heartbeat records.
- ✗
SecurityEvent | where EventID == 4624 | summarize count() by Computer
Why it's wrong here
SecurityEvent contains Windows security logs and successful sign-ins, which are unrelated to heartbeat reporting status.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse the Heartbeat table with other log tables (AzureActivity, Perf, SecurityEvent) that contain different data types, leading them to pick a query that looks for 'heartbeat' in the wrong table or uses irrelevant metrics like CPU or logon events.
Detailed technical explanation
How to think about this question
The Heartbeat table is populated by the Log Analytics agent (or Azure Monitor Agent) sending a record every 5 minutes by default, with fields like Computer, TimeGenerated, and Category. The `ago(15m)` function uses the query time as a reference, so if the last heartbeat is older than 15 minutes, it implies at least three missed heartbeat intervals, a common threshold for alerting on VM unavailability. In real-world scenarios, this query is often used in alert rules to detect VM outages or agent failures, but note that network latency or clock skew can cause false positives if the threshold is too tight.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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FAQ
Questions learners often ask
What does this AZ-104 question test?
Monitor and Maintain Azure Resources — This question tests Monitor and Maintain Azure Resources — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Heartbeat | summarize LastSeen=max(TimeGenerated) by Computer | where LastSeen < ago(15m) — Option A is correct because the Heartbeat table in Log Analytics records a heartbeat signal from Azure Monitor agents every 5 minutes by default. The query uses `summarize` to find the latest `TimeGenerated` per computer, then filters with `where LastSeen < ago(15m)` to identify VMs that have not sent a heartbeat in over 15 minutes, indicating they are likely offline or unresponsive.
What should I do if I get this AZ-104 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on AZ-104
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A help desk analyst needs to find Azure VM heartbeat records in Log Analytics and limit results to the last 30 minutes. Which two KQL elements should be used? Select two.
easy- ✓ A.where
- ✓ B.ago()
- C.summarize
- D.join
- E.extend
Why A: The `where` operator filters the result set based on a specified condition, which is essential for limiting records to those with a timestamp within the last 30 minutes. The `ago()` function returns a datetime value representing the current time minus a given timespan, allowing you to create a dynamic filter like `where TimeGenerated > ago(30m)`. Together, they enable precise time-based filtering in Kusto Query Language (KQL) for Log Analytics.
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Last reviewed: Jun 11, 2026
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