Here's how I would do it. YMMV.

#!/usr/bin/perl -w
use strict;
use IO::Socket::INET;

my %services = ( pop => [ 'mail.test.com', 110 ],
         smtp => [ 'mail.test.com', 25 ],
         web => [ 'test.com', 80 ],
         dns => [ 'test.com', 53 ],
         );
my %status;
$status{$_} = 'Up' for keys %services;

while (my ($name,$svc) = each %services) {
    my $sock = IO::Socket::INET->new(Timeout=>1,
                     PeerAddr => $svc->[0],
                     PeerPort => $svc->[1],
                     Proto => 'tcp' )
    or $status{$name} = 'Down';
}

while (my ($name,$sts) = each %status) {
    print "$name server is $sts\n";
}
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