AZ-104 Deploy and Manage Azure Compute Practice Question
A Linux VM deployed from a custom image shows only a black screen after reboot, and SSH never becomes available. The administrator needs to inspect the startup process without logging into the OS. Which two Azure features should be used? Select two.
⚠ Common exam trap
Candidates often confuse Azure Serial Console with SSH or RDP, assuming it requires the OS to be running, when in fact it works at the hypervisor level and is available even if the OS has not fully booted.
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
✓
Boot diagnostics
Boot diagnostics captures serial console output and screenshots of the VM during boot, allowing you to see kernel panics, driver failures, or bootloader errors even when the OS is unresponsive. Azure Serial Console provides a text-based console connection to the VM at the hypervisor layer, enabling interactive troubleshooting of the boot process (e.g., GRUB recovery, initramfs issues) without requiring network connectivity or SSH.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Boot diagnostics
Why this is correct
Boot diagnostics captures the VM's serial log output and host-side screenshots as the OS boots. When a custom Linux image only shows a blank screen, the captured console output reveals exactly where the boot fails—GRUB, kernel panic, missing drivers, or stuck on mounting a filesystem. This log is stored by Azure and can be retrieved from the portal or CLI even if the VM is unreachable. Therefore, it is the primary and most direct tool for observing the startup failure.
- ✓
Azure Serial Console
Why this is correct
Azure Serial Console provides an out-of-band, interactive serial connection to the VM so you can type commands directly at the Linux console without needing SSH or a working OS. If boot is incomplete, you gain real-time kernel and systemd log output and can interrupt GRUB, modify boot parameters, or fix fstab issues to bring the VM up. Because it works while the VM is allocated but before OS readiness, it both shows the boot problem and enables immediate remediation. For diagnostics, it complements boot diagnostics, but unlike screenshots it offers a live, interactive view.
- ✗
Azure Site Recovery
Why it's wrong here
Azure Site Recovery is a disaster recovery service that replicates entire Azure VMs to another region and orchestrates planned failover, unplanned failover, and failback. It never exposes the console, serial log, or boot-time output of a VM—it only manages replica creation and IP/mapping policies during a DR drill. Moreover, protecting a failing VM under Site Recovery would not reveal why the custom image is displaying only a blank boot screen. Thus, while it solves availability, it is not a boot diagnostic tool.
When this WOULD be correct
An administrator needs to ensure business continuity for a critical VM in the event of a regional outage. Azure Site Recovery would be the correct service to configure replication and failover to a secondary region.
- ✗
VM application health extension
Why it's wrong here
The VM application health extension reports application-level status by polling an HTTP endpoint or TCP port exposed by the workload inside the VM, feeding data to load balancer backend pools or scale set health. It cannot access or relay the Linux kernel boot messages, GRUB menu, or early console logs that would clarify why the custom image shows only an empty screen. Because the extension depends on the OS and application already running, it fails silently if the VM never reaches a bootable state. Therefore, it is unsuitable for boot-phase troubleshooting.
When this WOULD be correct
In a scenario where an application running on a VM is unresponsive and you need to automatically detect and recover from application failures, the VM application health extension would be correct, especially when combined with virtual machine scale set automatic repairs.
- ✗
Azure Backup restore point
Why it's wrong here
Azure Backup restore points are crash-consistency or application-consistency snapshots of the VM's managed disks used to restore data or recreate the VM from an earlier state. Selecting a restore point can overwrite the current custom-image disk, but it provides no historical or real-time console output explaining the current boot failure. The VM would still boot with the same problematic kernel or configuration unless you first diagnose the root cause. It is a recovery action, not a visibility mechanism.
When this WOULD be correct
When a VM has failed and needs to be restored to a previous known-good state due to data corruption or misconfiguration, and the question asks for a feature to recover the VM from a backup.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓Boot diagnosticsCorrect answer▾
Why this is correct
Boot diagnostics captures the VM's serial log output and host-side screenshots as the OS boots. When a custom Linux image only shows a blank screen, the captured console output reveals exactly where the boot fails—GRUB, kernel panic, missing drivers, or stuck on mounting a filesystem. This log is stored by Azure and can be retrieved from the portal or CLI even if the VM is unreachable. Therefore, it is the primary and most direct tool for observing the startup failure.
✗Azure Site RecoveryWrong answer — click to see why▾
Why this is wrong here
Azure Site Recovery is a disaster recovery service for replicating and failing over VMs, not for inspecting a VM's startup process or troubleshooting boot issues.
★ When this WOULD be the correct answer
An administrator needs to ensure business continuity for a critical VM in the event of a regional outage. Azure Site Recovery would be the correct service to configure replication and failover to a secondary region.
Why candidates choose this
Candidates may confuse Site Recovery's ability to 'recover' a VM with the ability to diagnose boot problems, or they may think it can restore a VM to a working state after a failed boot.
✗VM application health extensionWrong answer — click to see why▾
Why this is wrong here
The VM application health extension monitors application health and enables automatic repairs, but it does not provide out-of-band access to the OS startup process or console output, which is needed to diagnose a black screen and SSH failure.
★ When this WOULD be the correct answer
In a scenario where an application running on a VM is unresponsive and you need to automatically detect and recover from application failures, the VM application health extension would be correct, especially when combined with virtual machine scale set automatic repairs.
Why candidates choose this
Candidates may think the health extension can diagnose boot issues because it monitors VM health, but it only checks application-level health after the OS is fully booted, not the startup process itself.
✗Azure Backup restore pointWrong answer — click to see why▾
Why this is wrong here
Azure Backup restore point is used for recovering VM data from backups, not for inspecting the startup process or troubleshooting boot issues without OS access.
★ When this WOULD be the correct answer
When a VM has failed and needs to be restored to a previous known-good state due to data corruption or misconfiguration, and the question asks for a feature to recover the VM from a backup.
Why candidates choose this
Candidates may confuse restore points with recovery tools, thinking they can boot from a restore point to inspect the system, but restore points are for data recovery, not live troubleshooting.
Analysis generated from the official AZ-104blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Managed Identities for Azure Resources
Key term
Serial console
A serial console is a direct, low-level connection to a computer or network device that uses a serial port to let you send commands and receive text output, often for initial setup or emergency troubleshooting.
Key term
Hypervisor
A hypervisor is software that creates and runs virtual machines by allowing multiple operating systems to share a single hardware host.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.