Copy all A records from one Private DNS zone to another (or multiple)

Sync-PrivateDnsZone.ps1

using namespace Microsoft.Azure.Commands.PrivateDns.Models
filter Sync-AzPrivateDnsZone {
  [CmdletBinding(SupportsShouldProcess = $true)]
  param(
    #The zone to copy A records from
    [Parameter(Mandatory)][PSPrivateDNSZone]$SyncFrom,
    #The zone to copy A records into
    [Parameter(Mandatory, ValueFromPipeline)][PSPrivateDNSZone]$SyncTo,
    #How fast to create records
    [int]$ThrottleLimit = 10
  )
  $ErrorActionPreference = 'Stop'

  $srcRecords = $SyncFrom | Get-AzPrivateDnsRecordSet -RecordType 'A'
  $dstRecords = $SyncTo | Get-AzPrivateDnsRecordSet -RecordType 'A'

  $recordsToCopy = $srcRecords | Where-Object Name -NotIn $dstRecords.Name
  $recordActionParams = $recordsToCopy | Foreach-Object {
    $newRecordName = $PSItem.Name
    $newRecords = $PSItem.Records
    if (-not $PSCmdlet.ShouldProcess($SyncTo.Name, "Sync Record $newRecordName - $newRecords from $($SyncFrom.Name)")) {return}

    #This is a set of parameters we will splat to the New-AzPrivateDnsRecordSet
    return @{
      Name = $newRecordName
      RecordType = 'A'
      ResourceGroup = $SyncTo.ResourceGroupName
      ZoneName = $SyncTo.Name
      Ttl = 10
      PrivateDnsRecords = $PSItem.Records
    }
  }
  $recordActionParams | ForEach-Object -ThrottleLimit $ThrottleLimit -Parallel {
    New-AzPrivateDnsRecordSet @PSItem
  }
}