_
@s_dn=("c=US,ou=NUM,cn=foo", "c=DE,ou=NUM,cn=foo");
@dn=@s_dn;
my $number=0;
   for(my $i=0; $i<3; $i++,$number++)
   {
           for(@dn) { s/NUM/$number/g}
           # now I would save this dn and other stuff now.
           print @dn;
           print "\tou= should be $number\n";
   }