Remove all old DNS server entries from Forward and Reverse Zones in Active Directory DNS using Powershell

removeDNSServer.ps1

# Original idea: https://devblogs.microsoft.com/scripting/clean-up-domain-controller-dns-records-with-powershell/

# dnsSrv is only the only the hostname, no domain, of active DNS server, i.e. MYDNSSERVER
$dnsSrv = "<active-dns-server-hostname>"

# the server we are trying to remove, FQDN is Fully Qualified Domain Name, i.e. MYDNSSERVER.mydomain.local
$oldSrvFQDN = "<old-dns-FQDN>"
$oldSrvHost = "<old-dns-Hostname>"
$oldSrvIp = "<old-dns-ip-address>"

# get full list of zones
$zones = Get-DnsServerZone -ComputerName $dnsSrv | Select-Object -Property ZoneName

# try adjusting the loop for only a couple iterations while testing, replace with $zones.Length
for ($i = 0; $i -lt $zones.Length; $i++) {
  $dnsRecord = Get-DnsServerResourceRecord -ComputerName $dnsSrv -ZoneName $zones[$i].ZoneName
  
  $oldRecord = $dnsRecord |
    Where-Object {
      $_.RecordData.IPv4Address -eq $oldSrvIp -or
      $_.RecordData.NameServer -eq $oldSrvFQDN -or
      $_.RecordData.NameServer -eq $oldSrvHost -or
      $_.RecordData.DomainName -eq $oldSrvFQDN -or
      $_.RecordData.DomainName -eq $oldSrvHost
    }
    
    # Replace -WhatIf with -Force when ready to execute
    $oldRecord | Remove-DnsServerResourceRecord -ComputerName $dnsSrv -ZoneName $zones[$i].ZoneName -WhatIf
}