Fix fresh domain controller bootstrap

README.md

@@ -8,6 +8,9 @@ The repository starts from the current
 source and adds an SGU-specific provider, an mTLS-protected broker, Active
 Directory synchronization, deployment scripts, and tests.
 
+Ready-to-run bootstrap packages are published on the
+[releases page](https://github.lci.ulsa.mx/alexrg/SGU-CredentialProvider/releases).
+
 ## Authentication contract
 
 1. The Windows tile collects a `DO`, `AL`, or `AD` institutional key and a password.

docs/bootstrap-recovery.md

@@ -52,10 +52,17 @@ El proceso crea o configura de forma idempotente:
 - GPO de experiencia del equipo y restricciones de sesión SGU;
 - certificado de servidor no exportable y broker mTLS en TCP 8443;
 - recurso `\\SERVIDOR\Packages`, con lectura para Domain Computers;
-- RDP con NLA, WinRM/PowerShell Remoting y reglas administrativas sólo en el
+- RDP con NLA, WinRM/PowerShell Remoting y reglas administrativas limitadas a
-  perfil Domain;
+  la subred privada indicada, incluso si Windows tarda en reconocer el perfil
+  Domain después de la promoción;
 - pantalla, suspensión e hibernación en Nunca.
 
+En un servidor con dos NIC, el bootstrap desactiva el registro DNS de la NIC de
+Internet y obliga al servicio DNS a escuchar y publicar únicamente la IP fija
+privada. También vuelve a iniciar brevemente esa NIC privada si Windows Server
+2025 todavía la clasifica como Public al terminar la promoción. La salida HTTPS
+continúa por la NIC que tenga el gateway predeterminado.
+
 El broker arranca con una lista de clientes vacía. Eso no abre el servicio: mTLS
 rechaza todos los certificados hasta que el primer cliente registra el suyo.
 Los archivos opcionales colocados en `payload\server-content\Packages` al crear
@@ -129,8 +136,8 @@ validaciones.
 Desde el repositorio y con el SDK fijado en `global.json`:
 
 ```powershell
-.\scripts\New-SguBootstrapPackages.ps1 -Version 0.1.0
+.\scripts\New-SguBootstrapPackages.ps1 -Version 0.1.1
-.\scripts\Publish-GiteaRelease.ps1 -Version 0.1.0
+.\scripts\Publish-GiteaRelease.ps1 -Version 0.1.1
 ```
 
 El segundo comando usa `GITEA_TOKEN` sólo en memoria o, si no está definido,
@@ -139,7 +146,7 @@ la línea de comandos. Para empaquetar recursos institucionales adicionales:
 
 ```powershell
 .\scripts\New-SguBootstrapPackages.ps1 `
-  -Version 0.1.0 `
+  -Version 0.1.1 `
   -ServerContentPath C:\Preparacion\Packages
 ```
 

scripts/Deploy-AuthBroker.ps1

@@ -36,6 +36,9 @@ param(
     [int]$NtlmTimeoutSeconds = 20,
     [ValidateRange(2, 90)]
     [int]$ProfileTimeoutSeconds = 90,
+    [ValidateNotNullOrEmpty()]
+    [string[]]$FirewallRemoteAddress = @('LocalSubnet'),
+    [ipaddress]$FirewallLocalAddress,
     [switch]$CreateMissingOus,
     [switch]$DisableCertificateRevocationCheckForLab
 )
@@ -215,9 +218,32 @@ if ($PSCmdlet.ShouldProcess($installPath, 'Install the SGU Authentication Broker
         throw 'Could not enable recovery for non-crash SGUAuthBroker failures.'
     }
 
-    if (-not (Get-NetFirewallRule -DisplayName 'SGU Authentication Broker (mTLS)' -ErrorAction SilentlyContinue)) {
+    $firewallRule = Get-NetFirewallRule `
-        New-NetFirewallRule -DisplayName 'SGU Authentication Broker (mTLS)' `
+        -DisplayName 'SGU Authentication Broker (mTLS)' `
-            -Direction Inbound -Action Allow -Protocol TCP -LocalPort 8443 -Profile Domain | Out-Null
+        -ErrorAction SilentlyContinue
+    if (-not $firewallRule) {
+        $firewallParameters = @{
+            DisplayName = 'SGU Authentication Broker (mTLS)'
+            Direction = 'Inbound'
+            Action = 'Allow'
+            Protocol = 'TCP'
+            LocalPort = 8443
+            Profile = 'Any'
+            RemoteAddress = $FirewallRemoteAddress
+        }
+        if ($FirewallLocalAddress) {
+            $firewallParameters.LocalAddress = $FirewallLocalAddress.IPAddressToString
+        }
+        $firewallRule = New-NetFirewallRule @firewallParameters
+    }
+    else {
+        $firewallRule | Set-NetFirewallRule -Enabled True -Profile Any
+        $addressParameters = @{ RemoteAddress = $FirewallRemoteAddress }
+        if ($FirewallLocalAddress) {
+            $addressParameters.LocalAddress = $FirewallLocalAddress.IPAddressToString
+        }
+        $firewallRule | Get-NetFirewallAddressFilter |
+            Set-NetFirewallAddressFilter @addressParameters | Out-Null
     }
 
     Start-Service -Name $serviceName

scripts/Enable-SguServerRemoteManagement.ps1

@@ -1,5 +1,8 @@
 [CmdletBinding(SupportsShouldProcess)]
-param()
+param(
+    [ValidateNotNullOrEmpty()]
+    [string[]]$AllowedRemoteAddress = @('LocalSubnet')
+)
 
 $ErrorActionPreference = 'Stop'
 $identity = [Security.Principal.WindowsIdentity]::GetCurrent()
@@ -38,9 +41,12 @@ if ($PSCmdlet.ShouldProcess($env:COMPUTERNAME, 'Enable secure administrative RDP
 
     Set-Service -Name TermService -StartupType Automatic
     Start-Service -Name TermService
-    Get-NetFirewallRule -Name 'RemoteDesktop-UserMode-In-TCP','RemoteDesktop-UserMode-In-UDP' `
+    $remoteDesktopRules = @(Get-NetFirewallRule `
-        -ErrorAction SilentlyContinue |
+        -Name 'RemoteDesktop-UserMode-In-TCP','RemoteDesktop-UserMode-In-UDP' `
-        Set-NetFirewallRule -Enabled True -Profile Domain
+        -ErrorAction SilentlyContinue)
+    $remoteDesktopRules | Set-NetFirewallRule -Enabled True -Profile Any
+    $remoteDesktopRules | Get-NetFirewallAddressFilter |
+        Set-NetFirewallAddressFilter -RemoteAddress $AllowedRemoteAddress | Out-Null
 
     $enableRemoting = Start-Process `
         -FilePath "$env:SystemRoot\System32\WindowsPowerShell\v1.0\powershell.exe" `
@@ -57,9 +63,12 @@ if ($PSCmdlet.ShouldProcess($env:COMPUTERNAME, 'Enable secure administrative RDP
 
     Set-Service -Name WinRM -StartupType Automatic
     Start-Service -Name WinRM
-    Get-NetFirewallRule -Name 'WINRM-HTTP-In-TCP','WINRM-HTTP-In-TCP-NoScope' `
+    $winRmRules = @(Get-NetFirewallRule `
-        -ErrorAction SilentlyContinue |
+        -Name 'WINRM-HTTP-In-TCP','WINRM-HTTP-In-TCP-NoScope' `
-        Set-NetFirewallRule -Enabled True -Profile Domain
+        -ErrorAction SilentlyContinue)
+    $winRmRules | Set-NetFirewallRule -Enabled True -Profile Any
+    $winRmRules | Get-NetFirewallAddressFilter |
+        Set-NetFirewallAddressFilter -RemoteAddress $AllowedRemoteAddress | Out-Null
     Get-NetFirewallRule -Name 'WINRM-HTTP-In-TCP-PUBLIC' -ErrorAction SilentlyContinue |
         Disable-NetFirewallRule
 
@@ -74,8 +83,11 @@ if ($PSCmdlet.ShouldProcess($env:COMPUTERNAME, 'Enable secure administrative RDP
         'WMI-WINMGMT-In-TCP',
         'WMI-ASYNC-In-TCP'
     )
-    Get-NetFirewallRule -Name $administrativeRules -ErrorAction SilentlyContinue |
+    $enabledAdministrativeRules = @(Get-NetFirewallRule `
-        Set-NetFirewallRule -Enabled True -Profile Domain
+        -Name $administrativeRules -ErrorAction SilentlyContinue)
+    $enabledAdministrativeRules | Set-NetFirewallRule -Enabled True -Profile Any
+    $enabledAdministrativeRules | Get-NetFirewallAddressFilter |
+        Set-NetFirewallAddressFilter -RemoteAddress $AllowedRemoteAddress | Out-Null
 }
 
 [pscustomobject]@{
@@ -88,7 +100,8 @@ if ($PSCmdlet.ShouldProcess($env:COMPUTERNAME, 'Enable secure administrative RDP
         -Name UserAuthentication) -eq 1
     TermService = (Get-Service TermService).Status
     WinRM = (Get-Service WinRM).Status
-    FirewallProfile = 'Domain'
+    FirewallProfile = 'Any'
+    AllowedRemoteAddress = $AllowedRemoteAddress
     AdministrativeAccessOnly = $true
     AlwaysOnPowerPolicyApplied = $true
 }

scripts/Initialize-SguDomainController.ps1

@@ -171,8 +171,10 @@ function Ensure-OrganizationalUnit {
     )
 
     $distinguishedName = "OU=$Name,$Path"
-    $existing = Get-ADOrganizationalUnit -Identity $distinguishedName -Server $Server `
+    $escapedName = $Name.Replace('\', '\5c').Replace('*', '\2a').Replace('(', '\28').Replace(')', '\29')
-        -ErrorAction SilentlyContinue
+    $existing = Get-ADOrganizationalUnit -LDAPFilter "(ou=$escapedName)" `
+        -SearchBase $Path -SearchScope OneLevel -Server $Server -ErrorAction Stop |
+        Select-Object -First 1
     if (-not $existing) {
         New-ADOrganizationalUnit -Name $Name -Path $Path `
             -ProtectedFromAccidentalDeletion $true -Server $Server | Out-Null
@@ -180,6 +182,57 @@ function Ensure-OrganizationalUnit {
     return $distinguishedName
 }
 
+function Wait-ActiveDirectoryReady {
+    param(
+        [Parameter(Mandatory)][string]$ExpectedBaseDn,
+        [ValidateRange(1, 120)][int]$Attempts = 36,
+        [ValidateRange(1, 30)][int]$DelaySeconds = 5
+    )
+
+    for ($attempt = 1; $attempt -le $Attempts; $attempt++) {
+        try {
+            $rootDse = Get-ADRootDSE -Server localhost -ErrorAction Stop
+            if ($rootDse.DefaultNamingContext -eq $ExpectedBaseDn) {
+                return
+            }
+        }
+        catch {
+            if ($attempt -eq $Attempts) {
+                throw
+            }
+        }
+        Start-Sleep -Seconds $DelaySeconds
+    }
+    throw "Active Directory did not publish $ExpectedBaseDn before the readiness timeout."
+}
+
+function Wait-DnsZoneReady {
+    param(
+        [Parameter(Mandatory)][string]$ZoneName,
+        [Parameter(Mandatory)][ipaddress]$DnsServer,
+        [ValidateRange(1, 120)][int]$Attempts = 30,
+        [ValidateRange(1, 30)][int]$DelaySeconds = 2
+    )
+
+    for ($attempt = 1; $attempt -le $Attempts; $attempt++) {
+        try {
+            $soa = @(Resolve-DnsName $ZoneName -Type SOA -DnsOnly `
+                -Server $DnsServer.IPAddressToString -ErrorAction Stop |
+                Where-Object Type -eq SOA)
+            if ($soa.Count -gt 0) {
+                return
+            }
+        }
+        catch {
+            if ($attempt -eq $Attempts) {
+                throw
+            }
+        }
+        Start-Sleep -Seconds $DelaySeconds
+    }
+    throw "DNS did not load the $ZoneName zone before the readiness timeout."
+}
+
 function Set-PackageShare {
     param(
         [Parameter(Mandatory)][string]$Path,
@@ -234,6 +287,10 @@ function Set-PackageShare {
 }
 
 Assert-Administrator
+trap {
+    Write-BootstrapLog ("ERROR: " + $_.Exception.Message)
+    throw
+}
 $operatingSystem = Get-CimInstance Win32_OperatingSystem
 if ([int]$operatingSystem.ProductType -eq 1) {
     throw 'The domain controller bootstrap requires Windows Server, not a Windows client edition.'
@@ -379,24 +436,75 @@ if (-not $computer.Domain.Equals($DomainName, [StringComparison]::OrdinalIgnoreC
 }
 
 Write-BootstrapLog 'Finalizing Active Directory, DNS, policies, broker, shares, and remote management.'
-Import-Module ActiveDirectory -ErrorAction Stop
-$domain = Get-ADDomain -Identity $DomainName -Server $env:COMPUTERNAME
 
-$laboratoryOuDn = Ensure-OrganizationalUnit -Name 'Laboratorio' -Path $baseDn -Server $env:COMPUTERNAME
+# Once the machine is a DC, every active adapter must query the local DNS
-$usersOuDn = Ensure-OrganizationalUnit -Name 'Usuarios-SGU' -Path $baseDn -Server $env:COMPUTERNAME
+# service. Only the private domain adapter may publish its address in the AD
+# zone; otherwise clients can receive the DHCP/NAT address of the Internet NIC.
+Get-NetAdapter | Where-Object Status -eq 'Up' | ForEach-Object {
+    Set-DnsClientServerAddress -InterfaceIndex $_.ifIndex `
+        -ServerAddresses $ServerIPv4Address.IPAddressToString
+    Set-DnsClient -InterfaceIndex $_.ifIndex `
+        -RegisterThisConnectionsAddress:($_.Name -eq $NetworkInterfaceAlias)
+}
+
+Clear-DnsClientCache
+Register-DnsClient
+Import-Module ActiveDirectory -ErrorAction Stop
+Wait-ActiveDirectoryReady -ExpectedBaseDn $baseDn
+
+# A newly promoted Windows Server 2025 DC can retain the Public firewall
+# profile because network identification ran before local DNS and LDAP were
+# ready. A private-adapter bounce triggers the supported domain-detection path.
+$domainProfile = Get-NetConnectionProfile -InterfaceAlias $NetworkInterfaceAlias `
+    -ErrorAction SilentlyContinue
+if (-not $domainProfile -or $domainProfile.NetworkCategory -ne 'DomainAuthenticated') {
+    Write-BootstrapLog "Refreshing $NetworkInterfaceAlias so Windows detects the domain network profile."
+    Restart-NetAdapter -Name $NetworkInterfaceAlias -Confirm:$false
+    for ($attempt = 1; $attempt -le 15; $attempt++) {
+        Start-Sleep -Seconds 2
+        $domainProfile = Get-NetConnectionProfile -InterfaceAlias $NetworkInterfaceAlias `
+            -ErrorAction SilentlyContinue
+        if ($domainProfile -and $domainProfile.NetworkCategory -eq 'DomainAuthenticated') {
+            break
+        }
+    }
+}
+
+# Apply the single-address DNS listener only after any adapter refresh. That
+# avoids transient DNS socket errors while the private address is momentarily
+# unavailable, while still preventing the Internet/NAT address from being
+# published once finalization completes.
+New-ItemProperty `
+    -Path 'HKLM:\SYSTEM\CurrentControlSet\Services\DNS\Parameters' `
+    -Name PublishAddresses `
+    -PropertyType String `
+    -Value $ServerIPv4Address.IPAddressToString `
+    -Force | Out-Null
+$dnsServerSetting = Get-DnsServerSetting -All -WarningAction SilentlyContinue
+$dnsServerSetting.ListeningIPAddress = @($ServerIPv4Address)
+Set-DnsServerSetting -InputObject $dnsServerSetting -WarningAction SilentlyContinue | Out-Null
+Restart-Service DNS -Force
+Wait-DnsZoneReady -ZoneName $DomainName -DnsServer $ServerIPv4Address
+
+$adServer = 'localhost'
+$domain = Get-ADDomain -Identity $DomainName -Server $adServer
+$laboratoryOuDn = Ensure-OrganizationalUnit -Name 'Laboratorio' -Path $baseDn -Server $adServer
+$usersOuDn = Ensure-OrganizationalUnit -Name 'Usuarios-SGU' -Path $baseDn -Server $adServer
 foreach ($ouName in @('Docentes', 'Alumnos', 'Administrativos')) {
-    Ensure-OrganizationalUnit -Name $ouName -Path $usersOuDn -Server $env:COMPUTERNAME | Out-Null
+    Ensure-OrganizationalUnit -Name $ouName -Path $usersOuDn -Server $adServer | Out-Null
 }
 
 $remoteDesktopGroupName = 'SG-Laboratorio-Usuarios-RDP'
-$remoteDesktopGroup = Get-ADGroup -Identity $remoteDesktopGroupName -Server $env:COMPUTERNAME `
+$remoteDesktopGroup = Get-ADGroup -LDAPFilter "(sAMAccountName=$remoteDesktopGroupName)" `
+    -SearchBase $baseDn -SearchScope Subtree -Server $adServer `
     -ErrorAction SilentlyContinue
 if (-not $remoteDesktopGroup) {
     New-ADGroup -Name $remoteDesktopGroupName -SamAccountName $remoteDesktopGroupName `
         -GroupCategory Security -GroupScope Global -Path $laboratoryOuDn `
         -Description 'SGU users permitted to use Remote Desktop on laboratory clients.' `
-        -Server $env:COMPUTERNAME | Out-Null
+        -Server $adServer | Out-Null
-    $remoteDesktopGroup = Get-ADGroup -Identity $remoteDesktopGroupName -Server $env:COMPUTERNAME
+    $remoteDesktopGroup = Get-ADGroup -LDAPFilter "(sAMAccountName=$remoteDesktopGroupName)" `
+        -SearchBase $laboratoryOuDn -SearchScope OneLevel -Server $adServer
 }
 
 & (Join-Path $scriptsRoot 'Set-LabBrokerDns.ps1') `
@@ -444,16 +552,30 @@ if (Test-Path -LiteralPath $brokerConfigurationPath -PathType Leaf) {
     -PublishPath $brokerPublishPath `
     -ServerCertificateSubject $brokerDnsName `
     -AllowedClientThumbprints $allowedClientThumbprints `
-    -LdapHost $env:COMPUTERNAME `
+    -LdapHost $adServer `
     -BaseDn $baseDn `
     -DomainNetbios $DomainNetbios `
     -UpnSuffix $DomainName `
     -RemoteDesktopGroupDn $remoteDesktopGroup.DistinguishedName `
     -DefaultCompany 'La Salle' `
+    -FirewallLocalAddress $ServerIPv4Address `
+    -FirewallRemoteAddress "$($ServerIPv4Address.IPAddressToString)/$PrefixLength" `
     -CreateMissingOus `
     -DisableCertificateRevocationCheckForLab | Out-Null
 
-& (Join-Path $scriptsRoot 'Enable-SguServerRemoteManagement.ps1') | Out-Null
+# Remove stale A records registered by any non-domain/NAT adapter before its
+# dynamic DNS registration was disabled.
+$hostRecords = @(Get-DnsServerResourceRecord -ZoneName $DomainName `
+    -Name $env:COMPUTERNAME -RRType A -ErrorAction SilentlyContinue)
+foreach ($hostRecord in $hostRecords) {
+    if ($hostRecord.RecordData.IPv4Address.IPAddressToString -ne $ServerIPv4Address.IPAddressToString) {
+        Remove-DnsServerResourceRecord -ZoneName $DomainName -InputObject $hostRecord -Force
+    }
+}
+
+$privateSubnet = "$($ServerIPv4Address.IPAddressToString)/$PrefixLength"
+& (Join-Path $scriptsRoot 'Enable-SguServerRemoteManagement.ps1') `
+    -AllowedRemoteAddress $privateSubnet | Out-Null
 
 $contentPath = Join-Path $bootstrapRoot 'payload\server-content\Packages'
 if (Test-Path -LiteralPath $contentPath -PathType Container) {
@@ -463,6 +585,27 @@ if (Test-Path -LiteralPath $contentPath -PathType Container) {
 Set-PackageShare -Path $PackageSharePath -NetbiosName $DomainNetbios `
     -DomainSid $domain.DomainSID.Value
 
+$packageFirewallRule = Get-NetFirewallRule -DisplayName 'SGU Bootstrap Packages (SMB)' `
+    -ErrorAction SilentlyContinue
+if (-not $packageFirewallRule) {
+    New-NetFirewallRule `
+        -DisplayName 'SGU Bootstrap Packages (SMB)' `
+        -Direction Inbound `
+        -Action Allow `
+        -Protocol TCP `
+        -LocalPort 445 `
+        -LocalAddress $ServerIPv4Address.IPAddressToString `
+        -RemoteAddress $privateSubnet `
+        -Profile Any | Out-Null
+}
+else {
+    $packageFirewallRule | Set-NetFirewallRule -Enabled True -Profile Any
+    $packageFirewallRule | Get-NetFirewallAddressFilter |
+        Set-NetFirewallAddressFilter `
+            -LocalAddress $ServerIPv4Address.IPAddressToString `
+            -RemoteAddress $privateSubnet | Out-Null
+}
+
 & (Join-Path $scriptsRoot 'Set-SguDomainComputerPolicies.ps1') `
     -TargetOuDn $laboratoryOuDn -DomainController $env:COMPUTERNAME | Out-Null
 $userPolicyParameters = @{
@@ -493,6 +636,8 @@ $validation = [ordered]@{
     LaboratoryOu = $laboratoryOuDn
     UsersOu = $usersOuDn
     RemoteDesktopGroup = $remoteDesktopGroup.DistinguishedName
+    DomainNetworkProfile = [string](Get-NetConnectionProfile `
+        -InterfaceAlias $NetworkInterfaceAlias -ErrorAction SilentlyContinue).NetworkCategory
 }
 
 if ($validation.BrokerService -ne 'Running' -or

scripts/Publish-GiteaRelease.ps1

@@ -97,6 +97,7 @@ try {
     $releaseNotes = @"
 Bootstrap reproducible para el laboratorio SGU.
 
+- **Advertencia:** el bootstrap de servidor crea un bosque nuevo. No restaura los SID, contraseñas ni relaciones de confianza del bosque anterior; para conservarlos se requiere una recuperación de bosque desde una copia de estado del sistema.
 - `sgu-server-bootstrap-$Version.zip`: crea el bosque AD/DNS, OUs, grupo RDP, GPO, recurso `Packages`, broker mTLS y administración remota; se reanuda solo después del reinicio.
 - `sgu-client-bootstrap-$Version.zip`: registra un certificado mTLS único, instala y valida el Credential Provider antes de unir el equipo al dominio, habilita RDP/WinRM y se repara al arranque.
 - Windows Home se detecta y se rechaza con una explicación, ya que no admite unión a Active Directory ni RDP host.

scripts/Set-LabBrokerDns.ps1

@@ -8,18 +8,65 @@ param(
 )
 
 $ErrorActionPreference = 'Stop'
-$existing = Get-DnsServerResourceRecord -ZoneName $ZoneName -Name $RecordName -RRType A -ErrorAction SilentlyContinue
+$dnsReady = $false
-if ($existing) {
+for ($attempt = 1; $attempt -le 30; $attempt++) {
-    $current = @($existing.RecordData.IPv4Address.IPAddressToString)
+    try {
-    if ($current.Count -ne 1 -or $current[0] -ne $IPv4Address.IPAddressToString) {
+        $soa = @(Resolve-DnsName $ZoneName -Type SOA -DnsOnly -Server localhost `
-        # The fixed lab address is an explicit bootstrap input and may change
+            -ErrorAction Stop | Where-Object Type -eq SOA)
-        # when the server is rebuilt. Replace only this exact A record set.
+        if ($soa.Count -gt 0) {
-        $existing | Remove-DnsServerResourceRecord -ZoneName $ZoneName -Force
+            $dnsReady = $true
-        Add-DnsServerResourceRecordA -ZoneName $ZoneName -Name $RecordName -IPv4Address $IPv4Address
+            break
         }
+    }
+    catch {
+        # An AD-integrated zone can take a few seconds to load after DNS starts.
+    }
+    Start-Sleep -Seconds 2
 }
-else {
+if (-not $dnsReady) {
-    Add-DnsServerResourceRecordA -ZoneName $ZoneName -Name $RecordName -IPv4Address $IPv4Address
+    throw "DNS did not load the $ZoneName zone before the readiness timeout."
+}
+
+$recordReady = $false
+for ($attempt = 1; $attempt -le 5; $attempt++) {
+    $existing = @(Get-DnsServerResourceRecord -ZoneName $ZoneName -Name $RecordName `
+        -RRType A -ErrorAction SilentlyContinue)
+    $unwanted = @($existing | Where-Object {
+        $_.RecordData.IPv4Address.IPAddressToString -ne $IPv4Address.IPAddressToString
+    })
+    foreach ($record in $unwanted) {
+        Remove-DnsServerResourceRecord -ZoneName $ZoneName -InputObject $record -Force
+    }
+
+    $desired = @($existing | Where-Object {
+        $_.RecordData.IPv4Address.IPAddressToString -eq $IPv4Address.IPAddressToString
+    })
+    if ($desired.Count -eq 0) {
+        try {
+            Add-DnsServerResourceRecordA -ZoneName $ZoneName -Name $RecordName `
+                -IPv4Address $IPv4Address -ErrorAction Stop
+        }
+        catch {
+            # A record that becomes visible while an AD-integrated zone is
+            # finishing its load is harmless; the verified read below decides.
+        }
+    }
+
+    Start-Sleep -Milliseconds 250
+    $final = @(Get-DnsServerResourceRecord -ZoneName $ZoneName -Name $RecordName `
+        -RRType A -ErrorAction SilentlyContinue)
+    $finalAddresses = @($final | ForEach-Object {
+        $_.RecordData.IPv4Address.IPAddressToString
+    })
+    if ($finalAddresses.Count -eq 1 -and
+        $finalAddresses[0] -eq $IPv4Address.IPAddressToString) {
+        $recordReady = $true
+        break
+    }
+    Start-Sleep -Seconds 1
+}
+if (-not $recordReady) {
+    throw "The $RecordName.$ZoneName A record could not be set exclusively to $IPv4Address."
 }
 
 if ($ExternalForwarders.Count -gt 0) {