Script para monitorar DNS

Segue abaixo o script chamado de nanny.pl. Ele monitora seu servidor DNS e se for preciso reinicia o mesmo. Segue abaixo o script ou faça o download do mesmo aqui.
Não esqueça de colocar no crontab para executar o scrip de tempos em tempos.

#!/usr/bin/perl
#
# Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
# Copyright (C) 2000, 2001  Internet Software Consortium.
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.

# $Id: nanny.pl,v 1.9 2004/03/05 05:04:27 marka Exp $

# A simple nanny to make sure named stays running.

$pid_file_location = '/var/run/named.pid';
$nameserver_location = 'localhost';
$dig_program = 'dig';
$named_program =  'named';

fork() && exit();

for (;;) {
 $pid = 0;
 open(FILE, $pid_file_location) || goto restart;
 $pid = ;
 close(FILE);
 chomp($pid);

 $res = kill 0, $pid;

 goto restart if ($res == 0);

 $dig_command =
        "$dig_program +short . \@$nameserver_location > /dev/null";
 $return = system($dig_command);
 goto restart if ($return == 9);

 sleep 30;
 next;

 restart:
 if ($pid != 0) {
  kill 15, $pid;
  sleep 30;
 }
 system ($named_program);
 sleep 120;
}

by Osvaldo H Peixoto