- A
That the Recovery Services vault is in the same resource group as the VM.
Why wrong: Vault placement in the resource group is not the first thing to check for a guest-agent readiness error.
- B
That the Azure VM Agent service is installed and running inside the guest OS.
Azure VM Backup depends on the VM guest agent to coordinate extensions and backup integration. If the agent is missing, stopped, or unhealthy, backup jobs can fail immediately with a readiness message. Verifying the agent state is the correct first troubleshooting step before looking at policy, retention, or vault configuration.
- C
That soft delete is enabled on the vault.
Why wrong: Soft delete helps protect deleted backup data, but it does not resolve an unhealthy guest agent.
- D
That the subscription has enough free Azure Backup storage capacity.
Why wrong: Storage capacity concerns do not cause an immediate VM agent readiness failure on a new backup job.
Quick Answer
The answer is to verify that the Azure VM Agent service is installed and running inside the guest OS. This is the correct first step because the "VM agent not ready" error for Azure Backup on custom images means the Azure Backup extension cannot establish communication with the VM agent within the operating system. Since the VM was created from a custom image and no extensions have ever installed successfully, the root cause is almost always that the VM agent itself is missing or stopped, as backup extensions depend entirely on it. On the AZ-104 exam, this scenario tests your understanding that custom images often lack pre-installed agents, unlike marketplace images, and the common trap is to check network connectivity or permissions first. Remember the memory tip: "No agent, no backup" — the guest agent is the gatekeeper for all extension operations, so always start inside the OS.
AZ-104 Deploy and Manage Azure Compute Practice Question
This AZ-104 practice question tests your understanding of deploy and manage azure compute. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An Azure VM backup job starts failing immediately after protection is enabled. The error states that the VM agent is not ready. The VM was created from a custom image and no extensions have ever installed successfully. What should the administrator verify first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Clue:
"immediately / without restart"Why it matters: Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
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
That the Azure VM Agent service is installed and running inside the guest OS.
The error 'VM agent not ready' indicates that the Azure Backup extension cannot communicate with the VM agent inside the guest OS. Since the VM was created from a custom image and no extensions have ever installed successfully, the most likely cause is that the Azure VM Agent service is not installed or not running. The agent is required for backup extensions to function, so verifying its status inside the guest OS is the first troubleshooting step.
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.
- ✗
That the Recovery Services vault is in the same resource group as the VM.
Why it's wrong here
Vault placement in the resource group is not the first thing to check for a guest-agent readiness error.
- ✓
That the Azure VM Agent service is installed and running inside the guest OS.
Why this is correct
Azure VM Backup depends on the VM guest agent to coordinate extensions and backup integration. If the agent is missing, stopped, or unhealthy, backup jobs can fail immediately with a readiness message. Verifying the agent state is the correct first troubleshooting step before looking at policy, retention, or vault configuration.
Clue confirmation
The clue words "first", "immediately / without restart" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
That soft delete is enabled on the vault.
Why it's wrong here
Soft delete helps protect deleted backup data, but it does not resolve an unhealthy guest agent.
- ✗
That the subscription has enough free Azure Backup storage capacity.
Why it's wrong here
Storage capacity concerns do not cause an immediate VM agent readiness failure on a new backup job.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the issue is a vault configuration or capacity problem, but the 'VM agent not ready' error specifically points to a missing or non-functional guest agent, which is a common oversight when using custom images.
Detailed technical explanation
How to think about this question
The Azure VM Agent (waagent on Linux, WindowsAzureGuestAgent on Windows) is a guest OS service that enables Azure extensions, including the Backup extension (IaaSBcdrExtension). When a custom image is used, the agent must be manually installed and configured; otherwise, the Azure fabric cannot communicate with the VM to orchestrate backup snapshots. The agent communicates over TCP port 80 (HTTP) and 443 (HTTPS) with the Azure host, and its status can be checked via `Get-AzureRmVM -Status` or inside the OS using `services.msc` (Windows) or `systemctl status waagent` (Linux).
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Deploy and Manage Azure Compute — study guide chapter
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FAQ
Questions learners often ask
What does this AZ-104 question test?
Deploy and Manage Azure Compute — This question tests Deploy and Manage Azure Compute — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: That the Azure VM Agent service is installed and running inside the guest OS. — The error 'VM agent not ready' indicates that the Azure Backup extension cannot communicate with the VM agent inside the guest OS. Since the VM was created from a custom image and no extensions have ever installed successfully, the most likely cause is that the Azure VM Agent service is not installed or not running. The agent is required for backup extensions to function, so verifying its status inside the guest OS is the first troubleshooting step.
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.
Are there clue words in this question I should notice?
Yes — watch for: "first", "immediately / without restart". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
This AZ-104 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-104 exam.
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