Windows service trigger-start functionality introduced in Windows Server 2008 R2 and Windows 7 represents a significant evolution in service management. Unlike traditional startup types, trigger-start services remain dormant until specific system events (triggers) occur.

The fundamental distinction between automatic (trigger start) and manual (trigger start) lies in their initialization behavior:

// Automatic (Trigger Start)
- Service registry entry marked for automatic initialization
- SCM (Service Control Manager) loads service configuration at boot
- Service remains stopped until trigger event occurs
- Critical for services requiring early registration of triggers

// Manual (Trigger Start)
- SCM doesn't load configuration until explicitly needed
- First trigger attempt loads the configuration
- Slight delay on first trigger activation
- Suitable for non-critical services

The configuration choice impacts several operational aspects:

• Boot Time Performance: Automatic trigger-start services add minimal overhead during system startup as they register triggers but don't execute service code
• Error Handling: Failed automatic trigger-start services appear in event logs with source 'Service Control Manager'
• Dependency Resolution: Automatic configuration ensures dependent services can properly declare relationships

The monitoring scenario you described highlights an important implementation detail:

// PowerShell check for trigger-started services
Get-Service | Where-Object {
    $_.StartType -eq 'Automatic' -and 
    $_.Status -eq 'Stopped' -and
    (Get-ItemProperty -Path "HKLM:\\SYSTEM\\CurrentControlSet\\Services\\$($_.Name)").Start -eq 3
} | Select-Object Name,DisplayName

Switching from automatic to manual trigger-start won't affect basic functionality but may cause:

1. Delayed first-time trigger response (configuration load time)
2. Changed behavior in service dependency chains
3. Different event logging patterns

Consider these guidelines when configuring trigger-start services:

// C# service installation with trigger start
using (ServiceInstaller installer = new ServiceInstaller())
{
    installer.ServiceName = "MyTriggerService";
    installer.StartType = ServiceStartMode.Automatic; // For automatic trigger
    installer.ServicesDependedOn = new string[] { "EventLog" };
    
    // Custom trigger configuration would go here
    // Typically configured via separate INF file or post-install script
}

For mission-critical services requiring immediate trigger response, automatic configuration is preferred. Non-essential services can safely use manual trigger-start to reduce system overhead.

When triggers aren't firing as expected:

# Check registered triggers for a service
sc.exe qtriggerinfo "MyService"

# Sample output format:
START SERVICE
CUSTOM/5a4b8e9e-1e47-4770-af3c-f1a58e8a1ff1:DESKTOP-ABC123\Administrator
NETWORK EVENT:192.168.1.100:5985

When examining Windows services with trigger-based startup, the fundamental distinction between automatic (trigger start) and manual (trigger start) configurations lies in their initialization behavior:

• Automatic (Trigger Start): The service controller registers all triggers during system initialization, allowing immediate activation when trigger conditions occur
• Manual (Trigger Start): Triggers are only registered when the service is explicitly started (via API call or manual start), potentially causing delayed response to trigger events

Consider a print spooler service configured with device interface arrival triggers:

// Example trigger definition in service manifest
<triggers>
  <deviceInterfaceTrigger type="deviceInterfaceArrival">
    <id>{12345678-1234-1234-1234-123456789ABC}</id>
    <action>start</action>
  </deviceInterfaceTrigger>
</triggers>

With automatic (trigger start), the service immediately responds to printer connections. In manual (trigger start) configuration, the service must first be manually started before it will react to these events.

Monitoring tools often misinterpret trigger-started services. Here's how to properly check status:

// PowerShell command to check trigger-started services
Get-WmiObject -Class Win32_Service | 
Where-Object { $_.StartMode -match "trigger" } |
Select-Object Name, State, StartMode, Triggers

When changing from automatic to manual trigger start:

1. Dependent services may fail if they expect the service to be trigger-ready at boot
2. Event-driven architectures might experience initial missed events
3. System recovery scenarios may behave differently

For critical infrastructure services:

sc.exe config "MyService" start= delayed-auto
sc.exe triggerinfo "MyService" start/networkon

For less critical background services:

sc.exe config "MyService" start= demand
sc.exe triggerinfo "MyService" start/custom/event:MyCustomEvent