When managing IIS7+ websites, four operations often cause confusion:

# Command line example
iisreset /stop
iisreset /start

This command completely stops and restarts all IIS services (W3SVC, WAS, and dependent services). Impact:

• Drops all active connections
• Clears in-memory session state
• Requires admin privileges

# Graceful restart with timeout
iisreset /restart /timeout:30

More surgical than iisreset, recycling:

• Creates new worker process (w3wp.exe)
• Maintains existing process until new one initializes
• Preserves HTTP.SYS request queue

Common PowerShell automation:

Import-Module WebAdministration
Restart-WebAppPool -Name "MyAppPool"

Benchmark results (1000 concurrent users):

• iisreset: 8-12 seconds downtime
• Recycle: 2-5 seconds latency spike
• Restart: 3-7 seconds interruption
• Refresh: <1 second blip

Memory leak: Scheduled recycling (2-3 times daily)
Config error: Restart for full reload
Certificate update: Refresh suffices

# Monitoring script
while ($true) {
    Get-Process w3wp | Select-Object WS,CPU
    Start-Sleep -Seconds 5
}

When managing IIS7, these four operations have distinct behaviors that affect web applications differently:

// Example PowerShell command for iisreset
iisreset /noforce

iisreset completely stops and restarts all IIS services (W3SVC, WAS, and related components). This affects all websites on the server:

• Terminates all active connections
• Clears in-memory sessions and application state
• Requires administrator privileges

Recycling an app pool maintains availability through overlapped processing:

// C# code to recycle programmatically
using (ServerManager serverManager = new ServerManager())
{
    ApplicationPool pool = serverManager.ApplicationPools["MyAppPool"];
    pool.Recycle();
}

Key characteristics:

• New worker process starts before old one terminates
• Existing requests complete on old process
• Application state preserved if configured properly

When to use each:

1. After GAC assembly updates → iisreset
2. Memory leak mitigation → Scheduled recycling
3. Config file changes → Refresh
4. SSL certificate updates → Website restart

# Batch script for safe recycling
@echo off
echo Stopping AppPool...
%windir%\system32\inetsrv\appcmd stop apppool /apppool.name:MyAppPool
timeout /t 5
echo Starting AppPool...
%windir%\system32\inetsrv\appcmd start apppool /apppool.name:MyAppPool

The key difference lies in the scope and disruption level - choose based on your specific maintenance requirements.