Hyper-V & VMware

Your JD names "virtualisation platforms (VMware/Hyper-V)". Support engineers manage existing virtual machines far more often than they design new ones — so the practical skills matter more than architecture.

What you need to know

Concept	Why it matters in support
VM	A guest OS with virtual hardware
Host / hypervisor	The physical machine running them
Virtual hardware	Synthetic NIC, disk and CPU presented to the guest
vSwitch / vNIC	The virtual switch the host exposes
Snapshot / checkpoint	Point-in-time state — not a backup
Template	A powered-off VM cloned as a base image
vMotion / Live Migration	Moving a running VM between hosts
High availability / cluster	Keeping VMs up if a host fails
Overcommit	Allocating more vCPU/RAM than physically present

✖Snapshots are not backups

This is the single most important thing to know in virtualisation. A snapshot is a differential record against the parent, kept on the same storage as the VM. If the storage fails, the snapshot goes with it. Snapshots also cause performance degradation and can corrupt a VM's disk if left too long.

The correct answer, unprompted: "Snapshots are for short-term rollback before an update, not for long-term recovery. Backups must live on separate storage, ideally offsite."

Hyper-V essentials

# Where is it?
Get-VM

# Start, stop, and check state
Start-VM -Name "DC01"
Stop-VM -Name "DC01"
Get-VM | Select-Object Name, State, CPUUsage, MemoryAssigned

# Snapshots — check before blaming application performance
Get-VMSnapshot -VMName "DC01"

# Integration services
Get-VMIntegrationService -VMName "DC01"

# Host resources
Get-VMHost | Select-Object VirtualMachineProcessorPerformanceCount,
  AvailableMemoryMB

Cmdlet	Use
New-VM	Create a VM
Set-VMProcessor / Set-VMMemory	Right-size after creation
New-VHD	Attach a virtual disk
Add-VMNetworkAdapter	Add a NIC on a specific vSwitch
Get-VMSnapshot	Check for stale snapshots first
Start-VMHost / Stop-VMHost	Host maintenance
Move-VM / Move-VMStorage	Live migration / storage move
Export-VM / Import-VM	Clone to another host

★The support reflex

"The VM is slow." Before anything else, run Get-VMSnapshot. A machine with a year-old snapshot has an ever-growing .avhdx and a read/write penalty on every disk operation. It is the virtualisation equivalent of a user with 400 browser tabs.

VMware essentials

Task	vSphere client	PowerCLI
List VMs	Inventory view	Get-VM
Power state	Power menu	Start-VM, Stop-VM
Snapshots	Snapshots	Get-Snapshot
Console	Web console	—
Host management	Hosts and Clusters	Get-VMHost

Concept	Note
ESXi	The bare-metal hypervisor
vCenter	Central management for many hosts
HA	Restarts VMs if a host fails
DRS	Balances VMs across hosts by load
vSAN	Storage virtualisation across hosts
OVF/OVA	Exported appliance format

Networking in virtual environments

# Which vSwitch is the VM on?
Get-VMNetworkAdapter -VMName "DC01" | Select-Object SwitchName

# Add a second NIC — a domain controller wants two
Add-VMNetworkAdapter -VMName "DC01" -SwitchName "Production"

ℹWhy a DC needs two NICs

A domain controller should not be routing traffic between networks — it should only serve directory services. Two NICs keep the replication traffic separate from client traffic. Interviewers who run labs will know this.

VM sizing and performance

Symptom	Check
Host CPU pinned at 100%	Overcommit, or a runaway guest
Guest disk at 100%	Snapshot, or the host's storage
Guest slow but host idle	Guest's own configuration
Slow after migration	Wrong vSwitch, or a missing integration service
Boot loops	Snapshot corruption, or a missing driver

Get-VM | Select-Object Name,
  @{n='CPU%';e={[math]::Round($_.CPUUsage)}},
  @{n='RAMusedMB';e={[math]::Round($_.MemoryAssigned/1MB)}}

Virtualisation in the interview

◆The differentiating answer

Mention high availability and you move ahead of most L1/L2 candidates: "In production we'd cluster the hosts with HA and DRS, and the cluster restarts VMs on another host if one fails. Storage would be shared — vSAN or a SAN — with local datastores as a fallback."

Hands-on

Lab 1 has you install Hyper-V and build the whole environment this curriculum assumes.

Next

Technical Questions.