Lesson 5: Virtualization and Cloud Troubleshooting Challenge

Core path: 42 minutes

Virtualization and cloud add layers. They do not remove the technician's job of finding the first failed boundary.

Ticket A: every VM is slow

Evidence:

• host memory utilization is extremely high;
• host is paging heavily;
• all guests became slow after another large VM started.

The shared host-resource boundary is stronger than several simultaneous unrelated guest failures.

Ticket B: one VM has no network

Evidence:

• host network works;
• other VMs have connectivity;
• affected VM's virtual NIC is disconnected.

Stay at the virtual-device boundary.

Ticket C: legacy application VM

Evidence:

• legacy guest OS boots;
• required legacy application works;
• guest OS is unsupported and should not have general network access;
• user asks to bridge it directly to the production network.

Virtualization preserved compatibility. It did not remove the security risk. Design the narrowest network access appropriate to the fictional requirement.

Ticket D: VDI login fails

Evidence:

• local endpoint works;
• general internet/network access works;
• credentials are accepted by the organization identity service;
• VDI broker/service is unavailable.

Replacing the endpoint is not justified. The failed boundary is deeper in the centralized desktop path.

Ticket E: container vs VM misunderstanding

Evidence:

• a containerized application depends on a host kernel/runtime;
• the user expects it to behave like a complete independent guest OS.

Correct the architecture assumption before troubleshooting imaginary "missing VM hardware."

Ticket F: snapshot did not save the lab

Evidence:

• VM snapshot was stored on the same physical SSD as the VM;
• SSD failed completely;
• no independent backup/export exists.

The failure is recovery architecture, not proof that snapshots are useless.

Ticket G: synchronized deletion

Evidence:

• a user deletes a synchronized file;
• the deletion propagates to other synchronized devices;
• no independent backup/version recovery is available in the scenario.

File synchronization kept state consistent. It did not provide the expected independent backup.

Ticket H: cloud service unavailable

Evidence:

• local endpoint/network are healthy;
• provider status indicates a service outage;
• customer cannot repair provider infrastructure directly.

Document, communicate, and escalate rather than changing unrelated endpoint settings.

Final service record

For four tickets document:

virtualization/cloud model:
symptom:
last proven-good boundary:
first failed/unproven boundary:
security/network/storage dependency:
strongest theory:
controlled action or escalation:
verification:
remaining uncertainty:

Core 1 closure checkpoint

You should now be able to distinguish:

• sandbox/test-development, application virtualization, legacy, and cross-platform VM use cases;
• Type 1 vs Type 2 hypervisors;
• VDI vs a locally hosted VM;
• containers vs full VMs;
• private/public/hybrid/community cloud;
• IaaS/PaaS/SaaS;
• shared/dedicated resources, metering, elasticity, availability, file synchronization, and multitenancy.

Weeks 1–10 now close the planned Core 1 instructional block. The next repair block is Core 2 operating systems.