As a system administrator for over 15 years, I've seen this debate rage across countless organizations. The question isn't whether antivirus is important - we all agree it's crucial for endpoints. The real dilemma is whether it belongs on your critical Windows servers.

Let's start with the obvious exceptions:

• SQL Servers: The performance impact is simply too great. I've seen queries that normally take 2 seconds balloon to 20+ seconds with AV scanning.
• Web Servers: Most security professionals agree that proper firewall rules and application hardening provide better protection.

For these server roles, I recommend running a properly configured AV client:

Exchange Servers

Here's a PowerShell snippet to configure AV exclusions for Exchange:

Add-MpPreference -ExclusionPath "C:\Program Files\Microsoft\Exchange Server\V15"
Add-MpPreference -ExclusionProcess "EdgeTransport.exe"
Add-MpPreference -ExclusionProcess "MSExchangeFrontendTransport.exe"

Active Directory Domain Controllers

Critical exclusions for AD:

Add-MpPreference -ExclusionPath "%windir%\NTDS"
Add-MpPreference -ExclusionPath "%windir%\Sysvol"
Add-MpPreference -ExclusionProcess "lsass.exe"

For file servers, I recommend:

• Real-time scanning for incoming files
• Scheduled scans during off-hours
• Exclusions for database files and VM storage

When you must run AV on servers, these registry tweaks can help:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender]
"DisableScanOnStartup"=dword:00000001
"DisableRestorePoint"=dword:00000001
"DisableIOAVProtection"=dword:00000000

Implement these PowerShell checks to ensure your AV isn't causing issues:

# Check for high CPU usage by AV
Get-Process | Where-Object {$_.Name -like "*defender*" -and $_.CPU -gt 20} | Select ProcessName, CPU

# Verify exclusions are in place
Get-MpPreference | Select -ExpandProperty ExclusionPath

For servers where AV isn't feasible, consider:

• Application whitelisting via AppLocker
• Network segmentation
• Strict change control procedures

The decision ultimately comes down to your specific environment, compliance requirements, and risk tolerance. There's no one-size-fits-all answer, but with proper configuration and monitoring, AV can run safely on most enterprise servers.

After working with dozens of enterprise environments, I've seen this debate play out repeatedly. While everyone agrees that SQL Servers and web servers shouldn't run traditional AV clients, the question becomes murkier for other critical infrastructure.

The core dilemma revolves around balancing security requirements with system performance. Server workloads have different characteristics than endpoints:

// Example of AV scan impact measurement (PowerShell)
$scanTimes = @()
1..10 | ForEach-Object {
    $start = Get-Date
    # Simulate AV scan behavior
    Get-ChildItem -Path "C:\Program Files" -Recurse -Force | Out-Null
    $end = Get-Date
    $scanTimes += ($end - $start).TotalMilliseconds
}
$avgScanTime = ($scanTimes | Measure-Object -Average).Average
Write-Output "Average scan impact: $avgScanTime ms"

Modern enterprise AV solutions offer server-specific modes that minimize performance impact:

• Exchange Server: Requires special exclusions for database files and transaction logs
• Active Directory: Critical to exclude NTDS.dit and SYSVOL folders
• File Servers: Can benefit from real-time scanning but needs careful exclusion lists

Here's a PowerShell script to generate standard exclusions for Windows Servers:

# Generate AV exclusions for Windows Servers
$exclusions = @(
    "$env:SystemRoot\System32\GroupPolicy\Machine\Registry.pol",
    "$env:SystemRoot\System32\GroupPolicy\DomainSysvol",
    "$env:SystemRoot\NTDS\*.dit",
    "$env:SystemRoot\SYSVOL\*",
    "C:\Program Files\Microsoft SQL Server\*.mdf",
    "C:\Program Files\Microsoft SQL Server\*.ldf"
)

$exclusions | ForEach-Object {
    if (Test-Path $_) {
        Add-MpPreference -ExclusionPath $_
        Write-Output "Added exclusion: $_"
    }
}

For servers where traditional AV isn't appropriate:

# Enable Windows Defender Attack Surface Reduction Rules
Set-MpPreference -AttackSurfaceReductionRules_Ids @(
    "D4F940AB-401B-4EFC-AADC-AD5F3C50688A", # Block Office macros
    "5BEB7EFE-FD9A-4556-801D-275E5FFC04CC"  # Block executable content
) -AttackSurfaceReductionRules_Actions Enabled

For sensitive servers where you can't install AV, consider these monitoring alternatives:

# File integrity monitoring script
$criticalPaths = @("C:\Windows\System32", "C:\inetpub")
$baseline = @{}
foreach ($path in $criticalPaths) {
    $files = Get-ChildItem -Path $path -Recurse -File | Select-Object FullName, LastWriteTime, Length
    $baseline[$path] = $files
}

# Compare against baseline periodically
Compare-Object $baseline["C:\Windows\System32"] $currentScan -Property FullName, Length