#! /usr/bin/perl
use 5.014;
use strict;
use warnings;
use GetOpt:::Long;
use Net::DNS;

sub get_domains {
    return qw(schlittermann.de);
}

# query the serial from
# - the nameservers known from the ns records
# - from the primary master if this is not one of the 
#   NS for the zone
# - from a list of additional (hidden) servers
#
# OK - if the serial numbers are in sync
# WARNING - if there is some difference
# CRITICAL - if the serial cannot be found at one of the sources
