#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : DNS event 4013 -- waiting for Active Directory to signal it has completed initial synchronisation
    Fix   : Break the deadlock on a single-DC domain
    Source: https://jbtecwiz.com/support/srv-dns-4013

    Run as     : Elevated PowerShell
    Expect     : 15 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    This is the only DC, so there is no partner to wait for and the wait is
    pointless.

    HOW TO UNDO IT
    Set the value back to 1 and restart. Do this before adding a second DC.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 4"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  DNS event 4013 -- waiting for Active Directory to signal it has completed initial synchronisation' -ForegroundColor White
Write-Host '  Break the deadlock on a single-DC domain' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   15 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'Confirm it really is the only DC.' -Command {
    Get-ADDomainController -Filter * | Select-Object Name, Site, IPv4Address
}

Invoke-Step -Number 2 -Do 'Tell the DC not to require initial synchronisation before advertising.' -Why 'This is safe on a single DC and dangerous on several: it lets a DC advertise before it has caught up, which on a multi-DC domain can hand out stale data. Set it back to 1 if another DC is ever added.' -Command {
    New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Services\NTDS\Parameters' -Name 'Repl Perform Initial Synchronizations' -Value 0 -PropertyType DWord -Force
}

Invoke-Step -Number 3 -Do 'Restart the DC.' -Manual

Invoke-Step -Number 4 -Do 'Confirm DNS is answering for the zone.' -Command {
    Resolve-DnsName example.local -Server 127.0.0.1
}

Write-Rule "  Confirm it worked"
Show-Prose 'dcdiag passes and clients can authenticate.' 'White'
Write-Host ''
if (-not $DryRun) {
    dcdiag /v /test:dns
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/srv-dns-4013' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Set the value back to 1 and restart. Do this before adding a second DC.' 'DarkGray'
Write-Rule