# This Perl code adds or removes a replica server for the
# specified application partition

# ---------------------------------------------------------------
# Adapted from VBScript code contained in the book:
#      "Active Directory Cookbook" by Robbie Allen
# ISBN: 0-596-00466-4
# ---------------------------------------------------------------

# ------ SCRIPT CONFIGURATION ------
my $strAppPart = "<AppPartitionFQDN>"; # DNS name of the application partition

# Hostname of server to add as replica for app partition/
# This needs to match the common name for the DC's server $object/
my $strServer  = "<DomainControllerName>";  # e.g. dc01

# Set to 1 to add server as new replica or 0 to remove
my $boolAdd = 1;
# ------ END CONFIGURATION ---------
use Win32::OLE;
$Win32::OLE::Warn = 3;
# Constants taken from ADS_PROPERTY_OPERATION_ENUM
my $ADS_PROPERTY_APPEND = 3;
my $ADS_PROPERTY_DELETE = 4;

my $objRootDSE = Win32::OLE->GetObject("LDAP://RootDSE");

# ----------------------------------------------------------
# First need to find the NTDS Settings $object for the server
# ----------------------------------------------------------
my $strBase    = "<LDAP://cn=Sites," . $objRootDSE->Get("ConfigurationNamingContext") . ">;";
my $strFilter  = "(&(objectclass=server)(objectcategory=server)(cn=$strServer));";
my $strAttrs   = "cn,distinguishedName;";
my $strScope   = "subtree";
my $objConn = Win32::OLE->CreateObject("ADODB.Connection");
$objConn->{Provider} = "ADsDSOObject";
$objConn->Open;
my $objRS = $objConn->Execute($strBase . $strFilter . $strAttrs . $strScope);
if ($objRS->RecordCount != 1 ) {
   print "Did not find a match for server $strServer\n";
   exit;
}
else {
   $objRS->MoveLast;
   $strServerDN = "cn=NTDS Settings," . $objRS->Fields("distinguishedName")->Value;
   print "Found server: $strServerDN\n";
}

# ------------------------------------------------------------------
# Now need to find the crossRef $object for the application partition
# ------------------------------------------------------------------
$strBase    =  "<LDAP://cn=Partitions," . $objRootDSE->Get("ConfigurationNamingContext") . ">;";
$strFilter  = "(&(objectclass=crossRef)(objectcategory=crossRef)" .
             "(dnsRoot=" . $strAppPart . "));";
$strAttrs   = "cn,distinguishedName;";
$strScope   = "onelevel";
$objRS = $objConn->Execute($strBase . $strFilter . $strAttrs . $strScope);
if ($objRS->RecordCount != 1) {
   print "Did not find a match for application partition $strAppPart\n";
   exit;
}
else {
   $objRS->MoveLast;
   my $objAppPart = Win32::OLE->GetObject("LDAP://" . $objRS->Fields("distinguishedName")->Value );
   print "Found app partition: ", $objRS->Fields("distinguishedName")->Value, "\n";
}

# -----------------------------------------------
# Lastly, either add or remove the replica server
# -----------------------------------------------
if ($boolAdd == TRUE) {
   $objAppPart->PutEx($ADS_PROPERTY_APPEND, "msDS-NC-Replica-Locations", [$strServerDN]);
   $objAppPart->SetInfo;
   print "Added server to replica set\n";
}
else {
   $objAppPart->PutEx($ADS_PROPERTY_DELETE, "msDS-NC-Replica-Locations", [$strServerDN]);
   $objAppPart->SetInfo;
   print "Removed server from replica set\n";
}