Not quite sure what the question is but using strict and
warnings is a good start. The following code now at least
runs.
You seem to be mixing the object/non-object method of calling the CGI functions

#!/usr/bin/perl -w

use strict;
use CGI;
use CGI::Carp qw(fatalsToBrowser);
 
#$|++;
# $CGI::POST_MAX=100;
# $CGI::DISABLE_UPLOAD=1;
 my $q=new CGI;


print $q->header();
print $q->start_html(-title=>'check',-bgcolor=>"#000099",-text=>"#FF99
+33", -link=>"#FF3300",-alink=>"#FF3300",-vlink=>"#FF3300");

my %labels=('200.160.128.41'=>'HOST01',
            '200.160.128.42'=>'HOST02',
            '200.160.128.52'=>'HOST03',
            '200.160.136.130'=>'HOST04',
            '200.160.136.131'=>'HOST05',
            '200.160.136.132'=>'HOST06',
            '200.160.136.133'=>'HOST07',
            '200.160.136.136'=>'HOST08',
            '200.160.136.139'=>'HOST09',
            '200.160.136.140'=>'HOST10',
            '200.160.128.31'=>'HOST11',
            '200.160.128.88'=>'HOST12',
            '200.160.136.135'=>'HOST-GEST',
            '200.160.128.62'=>'HOSTSsql04',
            '200.160.128.43'=>'HOSTsql03',

            ) ;
print $q->start_form(-method=>'POST',-name=>'form1');
print $q->checkbox_group(-name=>'quale_server',
                                -values=>['200.160.128.41',
                                          '200.160.128.42',
                                          '200.160.128.52',
                                          '200.160.136.130',
                                          '200.160.136.131',
                                          '200.160.136.132',
                                          '200.160.136.133',
                                          '200.160.136.136',
                                          '200.160.136.139',
                                          '200.160.136.140',
                                          '200.160.128.31',
                                          '200.160.128.88',
                                          '200.160.136.135',
                                          '200.160.128.62',
                                          '200.160.128.43'],
                                #-default=>[keys %labels],
                                -linebreak=>'true',
                                #-size=>15,
                                -multiple=>'true',
        -labels=>\%labels,
        #-columns=>2
        );
 print $q->submit(-value=>'search'),$q->end_form();
 print $q->br;
 
 if (defined $q->param()){print "The keywords are: ",$q->em(join(", ",
+$q->param('quale_server')))}
##or @server=param('quale_server'); 
##########################################################
 print $q->end_html();
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